KR20120120309A - Process for production of diaryl oxalate - Google Patents

Abstract

The present invention is a method for producing diaryl oxalate including the step of transesterifying a dialkyl oxalate and / or an alkyl oxalate with an aryl alcohol in the presence of tetra (aryloxy) titanium as a catalyst. Titanium is supplied into the reaction system of the transesterification reaction as an aryl alcohol solution of tetra (aryloxy) titanium by reacting tetraalkoxytitanium with an excess of arylalcohol and removing the by-produced alkylalcohol. It is a manufacturing method.

Description

Production Method of Diaryl Oxalate {PROCESS FOR PRODUCTION OF DIARYL OXALATE}

The present invention relates to a method for producing diaryl oxalate by transesterifying dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol.

Diaryl oxalate is a compound that has been attracting attention in recent years because it is also useful as a raw material of diaryl carbonate widely used as a monomer when producing polycarbonate by melting by decarbonylation. Diaryl oxalate can be produced by transesterification of dialkyl oxalate and aryl alcohol, and the dialkyl oxalate used at that time can be produced from carbon monoxide and alkyl nitrite.

A series of processes have been proposed for producing diaryl carbonate from carbon monoxide and alkyl nitrite via dialkyl oxalate and diaryl oxalate (see Patent Document 1).

Further, transesterification is carried out in the presence of a catalyst for transesterifying dialkyl oxalate with aryl alcohol, and alkylaryl oxalate is produced as an intermediate while distilling off byproduct alkyl alcohol, and further unreacted in the presence of a catalyst. A method for producing diaryl oxalate has been proposed, wherein a heterogeneous reaction is carried out while dialkyl oxalate is distilled off to produce diaryl oxalate, and the reaction solution is distilled to recover diaryl oxalate. See Document 2.

In addition, as a catalyst used when preparing diaryl oxalate by transesterifying dialkyl oxalate and aryl alcohol in the presence of a catalyst, it is preferable to use a titanium compound, tin compound, lead compound, zirconium compound, molybdenum compound, and ytterbium compound. It is proposed and the titanium compound can be used most preferably especially (refer patent document 3).

Examples of the titanium compound include TiX ₃ , Ti (OAc) ₃ , Ti (OMe) ₃ , Ti (OEt) ₃ , Ti (OBu) ₃ , Ti (OPh) ₃ , TiX ₄ , Ti (OAc) ₄ , Ti (OMe ) ₄ , Ti (OEt) ₄ , Ti (OBu) ₄ , Ti (OPh) ₄ (where Ac is an acetyl group, Me is a methyl group, Et is an ethyl group, Bu is a butyl group, Ph is a phenyl group, X is a halogen atom) Although Ti (OPh) ₄ [tetra (phenoxy) titanium] is especially preferable as a catalyst which shows the outstanding transesterification ability.

However, tetra (aryloxy) titaniums, such as tetraphenoxytitanium, react with some water and decompose. In addition, tetra (aryloxy) titanium is solid at room temperature, and its purification requires complicated operations such as solid-liquid separation.

In addition, since it is difficult to use solid tetra (aryloxy) titanium for the continuous process for producing diaryl oxalate, it is necessary to melt it with heat or dissolve it in a solvent to make tetra (aryloxy) titanium as a liquid. However, tetra (aryloxy) titanium hardly dissolves in dialkyl oxalate, and also has low solubility in aryl alcohol, which causes an increase in process equipment, resulting in problems such as complexity in manufacturing a diaryl oxalate process.

Although the diaryl oxalate obtained by the said manufacturing method etc. turns into diaryl carbonate by decarbonylation, it becomes a raw material of polycarbonate by melt polycondensation reaction with bisaryl alcohol A as a final use, However, polycarbonate Nate is an engineering plastic with high transparency and is widely used for discs such as CDs and DVDs, plastic lenses, and the like. Therefore, in order to improve the transparency of resin, it is calculated | required that diaryl carbonate which is a raw material of polycarbonate, and diaryl oxalate which is its raw material do not contain a coloring component.

In addition, although the reaction and purification | separation operation are performed by using a distillation column of several stages as said manufacturing method, although the inventors examined the manufacturing method, although the compound containing a halogen atom is not contained in a reaction liquid, Corrosion and waste of material appear in contact parts of reaction liquids such as distillation towers made of austenitic stainless steel, such as SUS304, which are generally used as equipment materials for distillation towers, such as SUS304, reservoirs, and piping. Was found to be difficult.

In the above-mentioned production method, the distilled off alkyl alcohol contains impurities of low proportion generated during the transesterification reaction, and when they are recycled to the dialkyl oxalate production process, the yield and selectivity of the production reaction decrease, and the impurities produced. It was causing an undesirable condition such as an increase in.

Japanese Patent Publication No. 11-246490 Japanese Patent Publication No. 09-301920 Japanese Patent Laid-Open No. 2006-089417

An object of the present invention is to solve the above problems, and advantageous tetra (aryloxy) used in industrially performing transesterification reaction between dialkyl oxalate and / or alkylaryl oxalate and aryl alcohol to produce diaryl oxalate. It is an object of the present invention to provide a method for producing diaryl oxalate that efficiently supplies titanium into the reaction system of a transesterification reaction.

An object of the present invention is the production of diaryl oxalate which can produce high purity diaryl carbonate which does not contain a coloring component when producing diaryl carbonate by decarbonylating the diaryl oxalate produced by the above method. To provide a method or diaryl oxalate.

SUMMARY OF THE INVENTION An object of the present invention is a method for producing diaryl oxalate by an apparatus which is difficult to cause corrosion or waste of material and can be used industrially for a long time when transesterifying dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol. To provide.

An object of the present invention is to provide an industrially advantageous and efficient method for producing diaryl oxalate for producing diaryl carbonate via dialkyl oxalate and diaryl oxalate as raw materials of carbon monoxide, oxygen, and alkyl alcohol. In particular, diaryl oxalate for suppressing a decrease in reaction yield and selectivity of dialkyl oxalate due to peculiar impurities by transesterifying aryl alcohol having a phenolic hydroxyl group with dialkyl oxalate, It is to provide a manufacturing method.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors acquired the following knowledge, and came to complete this invention.

The inventors have found that under certain conditions, an arylalcohol solution of tetra (aryloxy) titanium can be produced by reacting tetraalkoxytitanium with an excess of arylalcohol and removing the by-produced alkylalcohol. In addition, the inventors of the present invention efficiently provide tetra (aryloxy) titanium, which is a target product, from the solution, and supply it directly to the step of transesterification of dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol. The knowledge that diaryl oxalate can be manufactured was acquired.

MEANS TO SOLVE THE PROBLEM In the said method, when distillation-purification so that the density | concentration of the titanium compound of the reaction liquid obtained by transesterification may become below a specific numerical value, this inventor acquired the knowledge that diaryl oxalate with a small coloring degree can be manufactured, Reached. That is, the present inventors have diligently studied to solve the above problems, and as a result, one of the coloring components contained in the diaryl oxalate used as a raw material when producing diaryl carbonate by decarbonylation of diaryl oxalate By discovering that it was a furan type compound and suppressing content of a furan type compound to a specific amount or less, the knowledge that diaryl oxalate with a small coloring degree was obtained, and reached this invention.

The inventors of the present invention, if the material of the device in contact with the reaction solution of the transesterification reaction is austenitic stainless steel containing 1 to 4% by weight of molybdenum while containing at least 10% by weight of nickel, corrosion and waste of material Was suppressed and the knowledge that it can manufacture continuously for a long time was acquired, and the present invention was reached.

In the above method, the present inventors first produce dialkyl oxalate using carbon monoxide, oxygen, and alkyl alcohol as a raw material, and then, by transesterification of dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol, alkyl by-produced. By recycling the dialkyl oxalate step to an ether compound contained in the alcohol at a specific amount or less, the inventors have found that industrially advantageous and efficient production can be achieved, and the present invention has been reached.

That is, this invention has the following structures specifically.

(1) A method for producing diaryl oxalate including the step of transesterifying dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol in the presence of tetra (aryloxy) titanium as a catalyst, which is tetra (aryloxy) Titanium is supplied to the reaction system of the transesterification reaction as an aryl alcohol solution of tetra (aryloxy) titanium by reacting tetraalkoxytitanium with an excess of aryl alcohol and removing the by-produced alkyl alcohol. It is a manufacturing method.

(2) The method for producing diaryl oxalate according to the above (1), wherein the titanium compound concentration of the reaction solution containing diaryl oxalate is 10 ppm by weight or less, followed by distillation purification.

(3) The production of diaryl oxalate as described in (1), wherein the material of the device in contact with the reaction solution of the transesterification reaction is an austenitic stainless steel containing 1 to 4% by weight of molybdenum while containing 10% by weight or more of nickel. It is a way.

(4) the process (A) according to the above (1), wherein dialkyl oxalate is produced by reacting carbon monoxide, oxygen and alkyl alcohol;

(B-1) a step of reacting dialkyl oxalate obtained in step (A) with aryl alcohol in the presence of an aryl alcohol solution of tetra (aryloxy) titanium to produce alkylaryl oxalate while removing the resulting alkyl alcohol,

The alkylaryl oxalate obtained in step (B-1) is heterogeneously reacted in the presence of an arylalcohol solution of tetra (aryloxy) titanium to produce diaryl oxalate while removing the resulting dialkyl oxalate and alkyl alcohol. 2) process,

(B-3) step of separating and recovering diaryl oxalate obtained in step (B-2)

/ RTI >

It is a manufacturing method of the diaryl oxalate which recycles alkyl alcohol to (A) process through (C) process which makes the ether compound content in the alkyl alcohol removed at the process (B-1) less than 1000 weight ppm.

(5) The method for producing diaryl oxalate according to any one of (1) to (4), wherein tetra (aryloxy) titanium is tetraphenoxycitane.

(6) The manufacturing method of diaryl oxalate in any one of said (1)-(5) whose tetraalkoxy titanium is tetraisopropoxy citanium.

(7) The molar ratio of the titanium atom and the aryl alcohol in the tetraalkoxy titanium (aryl alcohol / titanium atom) according to any one of the above (1) to (6), wherein the reaction of the tetraalkoxy titanium with the excess amount of aryl alcohol It is a manufacturing method of diaryl oxalate performed so that it may be 10-80.

(8) The method for producing diaryl oxalate according to any one of (1) to (7), wherein the reaction of tetraalkoxy titanium with an excess of aryl alcohol is carried out at a reaction temperature of 160 to 300 ° C.

(9) The method for producing diaryl oxalate according to any one of (1) to (8), wherein the reaction of tetraalkoxy titanium with an excess of aryl alcohol is carried out in a reaction distillation column.

(10) The method for producing diaryl oxalate according to (9), wherein the reflux ratio of tetraalkoxy titanium and excess aryl alcohol in the reaction distillation column is 3 to 40.

(11) The molar ratio (aryl alcohol / titanium atom) per unit time of the tetraalkoxy titanium and the excess amount of aryl alcohol in the tetraalkoxy titanium is 40 to the reaction distillation column according to (9) or (10). It is a manufacturing method of diaryl oxalate supplied continuously to be 80.

(12) The oil fraction containing the by-produced alkyl alcohol according to any one of (1) to (11), wherein tetraalkoxytitanium and an excess amount of aryl alcohol are supplied to the reaction distillation column for reaction. By extracting the oil containing tetra (aryloxy) titanium and aryl alcohol from the bottom part, the aryl alcohol solution of tetra (aryloxy) titanium from which the by-produced alkyl alcohol was removed is obtained, and it supplies to a transesterification reaction process. It is a manufacturing method of diaryl oxalate.

(13) The arylalcohol solution of tetra (aryloxy) titanium according to (12), wherein tetra (aryloxy) titanium and arylalcohol are continuously extracted from the bottom of the reaction distillation column, and the alkyl alcohol produced byproducts is continuously removed. It is a manufacturing method of diaryl oxalate supplied to a transesterification reaction process.

(14) The production of diaryl oxalate as described in any one of (1) to (13), wherein the material of the apparatus in contact with the reaction solution of the transesterification reaction is an austenitic stainless steel containing 16.00 to 18.00 wt% of chromium. It is a way.

(15) The method for producing diaryl oxalate according to (14), wherein the material of the device is austenitic stainless steel that contains substantially no nitrogen atoms.

(16) The method for producing diaryl oxalate according to (15), wherein the material of the device is SUS316-based austenitic stainless steel defined in JIS G 4304.

(17) In the above (16), the austenitic stainless steel is a method for producing diaryl oxalate, which is SUS316 or SUS316L specified in JIS G 4304.

(18) The method for producing diaryl oxalate according to any one of (1) to (17), wherein the apparatus is a purification tower of diaryl oxalate, a reaction vessel for a transesterification reaction, or a reaction distillation column.

(19) The method for producing diaryl oxalate according to (4), wherein the ether compound content in the alkyl alcohol is 300 ppm or less in the step (C).

(20) The method for producing diaryl oxalate according to (4) or (19), wherein the ether compound in the step (C) is an alkylaryl ether.

(21) The compound according to any one of (4), (19) or (20), wherein, in the step (B-3), an oxalic acid ester having at least one aryl ester group or a decomposition product thereof is fries rearranged. It is a manufacturing method of diaryl oxalate which removes the compound which has a hydroxyl group and an aryloxy group, or the compound in which the hydroxyl group and aryloxy group of the said compound reacted in the molecule | numerator, or between molecules, or derivatives thereof.

(22) It is a manufacturing method of diaryl carbonate which decarbonylates the diaryl oxalate manufactured by the method in any one of said (1)-(21) in presence of a phosphorus compound.

(23) It is a manufacturing method of polycarbonate which makes diaryl carbonate manufactured by the method as described in said (22) react with bisphenol A in presence of basic alkali metal salt.

According to the method for producing diaryl oxalate of the present invention, an arylalcohol solution of tetra (aryloxy) titanium used as a catalyst can be produced at a high rate by reacting tetraalkoxytitanium with an excess of arylalcohol under specific conditions. .

Furthermore, since the produced tetra (aryloxy) titanium is not isolated and refined, it is supplied as it is to the process of transesterifying the dialkyl oxalate and / or alkylaryl oxalate and aryl alcohol as an aryl alcohol solution, and the purification process is greatly simplified. Contact with deteriorated or decomposed substances such as residence time, thermal history to tetra (aryloxy) titanium, water, etc., by reducing the environmental load due to the simplification of manufacturing equipment, the reduction of purification solvents and the like, and the simplification of the process. This reduction can reduce the degradation products, thereby improving the selectivity of the diaryl oxalate and improving the reaction efficiency.

According to the production method of the diaryl oxalate of the present invention, the content of the furan compound can be suppressed to a specific amount or less to obtain a highly non-coloring diaryl oxalate that does not contain coloring components such as red or yellowish color. By carbonylation, highly non-coloring diaryl carbonate can be prepared. Diaryl oxalate obtained by the present invention is particularly useful as a raw material such as polyoxamide resin used for optical materials such as optical lenses and optical filters, and diaryl carbonate obtained from diaryl oxalate is similarly an optical material. It is very useful as a raw material of the polycarbonate resin used for.

According to the production method of the diaryl oxalate of the present invention, since corrosion and material waste at the place of contact with the reaction liquid can be suppressed, repair and replacement of the contact portion with the liquid such as a distillation column, a tank, and a pipe for a long time can be performed. There is no need, and it is very advantageous industrially. In addition, there is no fear of liquid leakage due to corrosion, and the improvement of safety can also be expected. As a result, the diaryl carbonate which manufactures a diaryl oxalate as a raw material can be industrially produced freely and stably from a cost viewpoint.

According to the production method of the diaryl oxalate of the present invention, even if the alkyl alcohol produced by transesterification of dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol is recycled to the production process of dialkyl oxalate, high yield and high Selectively, dialkyl oxalate can be prepared.

Description of the element | module described below is an example (representative example) of embodiment of this invention, and is not specified by these content.

[Dialkyl oxalate]

The dialkyl oxalate used in the present invention is not particularly limited, and two alkyl groups in the dialkyl oxalate molecule may be the same or different. Examples of the dialkyl oxalate include, for example, oxalic acid such as dimethyl oxalate, diethyl oxalate, dipropyl oxalate, diisopropyl oxalate, dibutyl oxalate, dipentyl oxalate, dihexyl oxalate, diheptyl oxalate, dioctyl oxalate, and dioxyl oxalate. Dialkyl can be used. Among the dialkyl oxalates, dialkyl oxalate having a linear or branched alkyl group having 1 to 10 carbon atoms is preferable from the viewpoint of the reaction rate of the transesterification reaction and the ease of removing the by-produced alkyl alcohol, and dimethyl oxalate or oxalic acid Ethyl is particularly preferred.

[Method for producing dialkyl oxalate]

It does not specifically limit about the manufacturing method of the dialkyl oxalate used by this invention, The thing manufactured by either method can also be used. Below, the (A) process of manufacturing the dialkyl oxalate used by this invention is demonstrated. The step (A) is a step of producing dialkyl oxalate by reacting carbon monoxide, oxygen, and alkyl alcohol.

[(A) step]

In addition to the alkyl alcohol and oxygen used as the raw materials in this step, nitrogen monoxide is reacted to produce alkyl nitrite, which is further reacted with carbon monoxide to produce dialkyl oxalate. A platinum group metal catalyst is preferably used as the catalyst for reacting the alkyl nitrite and carbon monoxide. The platinum group metal catalyst may be a platinum group metal or a compound thereof, but the platinum group metal compound is preferably used in the form of a platinum group metal.

Examples of the platinum group metals include platinum metals, palladium metals, rhodium metals, iridium metals, and the like, and examples thereof include inorganic acid salts of these metals (nitrates, sulfates, phosphates, etc.), halides ( Chlorides, bromide and the like), organic acid salts (acetates, oxalates, benzoates, etc.), complexes and the like. Of the platinum group metals or compounds thereof, palladium metals or compounds thereof are particularly preferred.

As a palladium compound, For example, inorganic salts of palladium (palladium nitrate, palladium sulfate, palladium phosphate, etc.), halides of palladium (palladium chloride, palladium bromide, etc.), organic salts of palladium (palladium acetate, palladium oxalate, palladium benzoate) Etc.) or a complex of palladium (alkyl phosphines such as trimethyl phosphine, aryl phosphines such as triphenyl phosphine, alkyl phenyl phosphines such as diethyl phenyl phosphine or aryl phosphites such as triphenyl phosphite, etc. Complexes having a ligand as the ligand), and the like.

As the platinum group metal catalyst, it is industrially used to use a solid catalyst in which a platinum group metal or a compound thereof is supported on an inert carrier in terms of platinum group metal, preferably 0.01 to 10% by weight, more preferably 0.2 to 2% by weight. desirable. As the inert carrier, for example, palladium metal or a compound thereof may be activated carbon, alumina (α-alumina, etc.), silica, diatomaceous earth, pumice, zeolite, molecular sieve, spinel and the like. When using a solid catalyst in which a platinum group metal compound is supported on a carrier, the supported platinum group metal compound is previously reduced to a platinum group metal in a reducing substance such as hydrogen, or in a reducing substance such as carbon monoxide in a reactor before the reaction. It is preferable to reduce and use it with a platinum group metal. In addition, the platinum group metal catalyst is supported on the carrier by a known method (impregnation method, evaporation drying method, etc.).

The platinum group metal catalyst may contain, for example, iron or a compound thereof. As iron or its compound, a metal iron, an iron (II) compound, or an iron (III) compound is mentioned. As the iron (II) compound, for example, ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous ammonium sulfate, ferrous lactate, ferrous hydroxide and the like are preferably used. As the compound (III), it is preferable to use ferric sulfate, ferric nitrate, ferric chloride, ferric sulfate ammonium, ferric lactate, ferric hydroxide, ferric citrate and the like. Iron or a compound thereof is used such that the platinum group metal: iron (atomic ratio) is preferably in the range of 10000: 1 to 1: 4, more preferably 5000: 1 to 1: 3. In addition, catalysts containing iron or compounds thereof are prepared by known methods.

The carbon monoxide used in the step (A) may be pure, but may be diluted with an inert gas such as nitrogen, or may contain a small amount of hydrogen gas or methane. In the present invention, carbon monoxide produced by decarbonylation of diaryl oxalate described later can also be used. The carbon monoxide produced by the decarbonylation of diaryl oxalate is fed to an alkyl nitrite regeneration process after alkali treatment to replenish carbon monoxide consumed in the reaction or carbon monoxide lost by purging the circulating gas. It is preferred to be reused at.

In the reaction of step (A), for example, dialkyl oxalate can be produced by contacting a source gas containing carbon monoxide and alkyl nitrite in the presence of a platinum group metal catalyst in the gas phase. At this time, it is preferable that the contact time of source gas and a platinum group metal catalyst is 10 second or less, and also 0.2 to 5 second, and reaction temperature is 50-200 degreeC, and also 80-150 degreeC is preferable. Further, the reaction pressure is preferably from normal pressure to 10 kg / cm 2 G, and from normal pressure to 5 kg / cm 2 G, but particularly preferably from 2 to 5 kg / cm 2 G. As the reactor, a single tube or a multi-tube heat exchanger reactor is effective.

The concentration of carbon monoxide in the source gas is preferably in the range of 2 to 90% by volume. In addition, although the concentration of the alkyl nitrite in the source gas can be varied within a wide range, it is preferable to have the alkyl nitrite present so that the concentration in the source gas is 1% by volume or more in order to obtain a satisfactory reaction rate. It is preferable that the density | concentration of the alkyl nitrite in source gas is 5-30 volume%, for example.

In the step (A), a product (for example, a reaction gas) containing dialkyl oxalate is obtained. This product (e.g., reaction gas) is then led to a condenser, cooled to a temperature at which the dialkyl oxalate condenses, and separated into a condensate containing dialkyl oxalate and a non-condensable gas containing nitrogen monoxide. At this time, in order to prevent the dialkyl oxalate from entraining in the non-condensing gas, it is preferable to contact 100 parts by weight of the product with 0.001 to 0.1 parts by volume of alkyl alcohol at 30 to 60 ℃. Moreover, it is preferable that the operation pressure of this process is normal pressure-10 kg / cm <2> G, It is more preferable that it is normal pressure-5 kg / cm <2> G, It is especially preferable that it is under the pressurization of 2-5 kg / cm <2> G.

Next, dialkyl oxalate is separated and recovered from the condensate. This operation is performed by, for example, directing the condensate to a distillation column and distilling it in a normal operation so that the condensate contains a small amount of by-products such as dialkyl carbonate and alkyl formate, in addition to dialkyl oxalate. It is supplied to the process of carrying out the transesterification reaction of the separated-recovered dialkyl oxalate and / or alkylaryl oxalate, and aryl alcohol.

On the other hand, the separated non-condensable gas contains nitrogen monoxide produced in the step (A) in addition to unreacted carbon monoxide and alkyl nitrite, which is led to a process for regenerating to alkyl nitrite. The regeneration of the alkyl nitrite is conducted by inducing a non-condensable gas to the bottom of the regeneration tower and contacting with molecular oxygen and alkyl alcohol (reacting nitrogen monoxide with molecular oxygen and alkyl alcohol). And the gas (regeneration gas) derived from a regeneration tower is circulated-supplied to process (A), and is reused. At this time, in addition to the alkyl alcohol newly supplied from the outside of the system, the alkyl alcohol used is an alkyl alcohol produced and recovered in the transesterification step described below.

As the molecular oxygen, oxygen gas or air is used. As the regeneration tower, conventional gas-liquid contact devices such as a packed column, bubble column, spray tower, and single column are used. In the regeneration of alkyl nitrite, the reaction is controlled so that the concentration of nitrogen monoxide in the regeneration gas is 2 to 7% by volume. For this reason, 0.08-0.2 mol of molecular oxygen is supplied with respect to 1 mol of nitrogen monoxide in the non-condensing gas introduce | transduced into a regeneration tower, and below the boiling point of the alkyl alcohol in the pressure at the time of regeneration (for example, alkyl from 0 degreeC At a temperature of up to the boiling point of the alcohol, it is preferable to contact the non-condensable gas with molecular oxygen and alkyl alcohol. It is preferable that the supply amount of alkyl alcohol is 1-5 volume parts with respect to 1 volume part of nitrogen monoxide in a non-condensing gas, and 0.5 to 20 second of contact time is preferable. Moreover, it is preferable that operation pressure is 10 kg / cm <2> G from normal pressure, It is more preferable that it is 5 kg / cm <2> G from normal pressure, It is especially preferable that it is 2-5 kg / cm <2> G.

In the alkyl nitrite regeneration step, carbon monoxide treated with alkali (washed with an aqueous alkali solution and / or contact with an alkali-based adsorbent, etc.) is supplied. The alkali treated carbon monoxide is preferably introduced at the bottom of the regeneration tower. At the bottom of the regeneration tower, for example, non-condensable gas in the gas generated in the step (A) may be introduced by being mixed with the non-condensable gas from a supply line supplied to the alkyl nitrite regeneration process, or may be introduced separately. By supplying the carbon monoxide alkali-treated to the alkyl nitrite regeneration process, the fall of the selectivity of the dialkyl oxalate in a process (A), and the fall of catalyst activity can be suppressed effectively.

When the step (A) is carried out in a continuous step, the carbon monoxide consumed in the reaction and the carbon monoxide lost out of the system can be effectively replenished by the supply of carbon monoxide. In addition, to supplement the nitrogen component lost to the system, alkyl nitrite, nitrogen oxides (nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetraoxide, etc.), or nitric acid are introduced at the bottom of the regeneration tower of the alkyl nitrite regeneration process. In this way, carbon monoxide is replenished (a nitrogen component is also replenished as necessary), and the gas containing the regenerated alkyl nitrite (regeneration gas) is circulatedly supplied to the step (A).

[Aryl alcohol]

As the aryl alcohol used in the present invention, for example, phenol, o-cresol, m-cresol, p-cresol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2,3-dimethylphenol, 2 , 4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol and the like. Especially, a phenol is preferable at the point of reactivity and versatility.

[Diaryl oxalate]

The diaryl oxalate produced in the present invention is not particularly limited, but for example, diphenyl oxalate, bis (o-methylphenyl), oxalic acid bis (p-methylphenyl), oxalic acid bis (o-ethylphenyl) and bisoxalic acid bis (p) -Ethylphenyl) etc. are mentioned.

[Catalyst (ester exchange catalyst)]

In the production method of the oxalic acid diaryl the present invention, specifically, the titanium compound is preferred as the catalyst for reacting the transesterification, and is _{TiX 3, Ti (OAc) 3} , Ti (OBu) 3, Ti (OPh) 3, TiX 4 , Ti (OAc) ₄ , Ti (OBu) ₄ , Ti (OPh) ₄ , and the like. However, Ac represents an acetyl group, Bu represents a butyl group, Ph represents a phenyl group, and X represents a halogen atom. Among them, Ti (OPh) ₄ [tetraphenoxycitane] having the same substituent as the aryl alcohol of the raw material is particularly preferable in that it does not by-produce impurities.

It is difficult or difficult to obtain industrial quantities of tetra (aryloxy) titanium on the market, but the arylalcohol solution of tetra (aryloxy) titanium is easily reacted by easily reacting tetraalkoxytitanium and aryl alcohol, which are readily available on an industrial scale. Can be generated. Although there is no restriction | limiting in particular as tetraalkoxy titanium, Although tetramethoxy titanium, tetraisopropoxytitanium, tetra-n-butoxy titanium, etc. which are easy to obtain are mentioned, tetraisopropoxy is easy in the point of handling and obtaining. Titanium is preferred.

The aryl alcohol solution of tetra (aryloxy) titanium can be manufactured by removing the by-product alkyl alcohol which heats tetraalkoxy titanium and aryl alcohols, such as tetraisopropoxytitanium, out of the system. It is preferable to perform reaction of tetraalkoxy titanium and an excess amount of aryl alcohol in a reaction distillation column. Although there is no restriction | limiting in the method of removing the by-produced alkyl alcohol out of the system, Since aryl alcohol and tetraalkoxy titanium also have a vapor pressure, the method of removing an alkyl alcohol from a column top using a distillation column is preferable, and continuously Since it can be produced, tetraalkoxy titanium and aryl alcohol are supplied as reaction distillation to extract an aryl alcohol solution of tetra (aryloxy) titanium from the bottom and out of the system while partially refluxing the alkyl alcohol from the column top. The extraction method is more preferable.

Since the conversion rate of tetraalkoxy titanium may fall when it supplies to the bottom of a distillation column about supply place of a raw material in a distillation column, it is preferable to supply the tetraalkoxy titanium and aryl alcohol which are raw materials from the side part of a distillation column so that a reactive distillation part may be provided. Do. As the type of the reaction distillation column, a borane perforated plate distillation column such as Oldershaw type, a packed distillation column packed with various fillers, and the like can be used, but not limited thereto.

When the tetraalkoxy titanium is reacted with aryl alcohol, even if there is no solvent, the reaction proceeds sufficiently. However, if necessary, a solvent such as toluene azeotropic with the by-produced alkyl alcohol may be added.

It is preferable to continuously supply the aryl alcohol solution of tetra (aryloxy) titanium to the process of transesterifying dialkyl oxalate and / or alkylaryl oxalate, and aryl alcohol.

Although the aryl alcohol solution of tetra (aryloxy) titanium may be produced intermittently, it is preferable to manufacture continuously. In the case of continuously preparing an aryl alcohol solution of tetra (aryloxy) titanium, tetraalkoxy titanium and aryl alcohol are fed to the reaction distillation column continuously or intermittently. It is preferable to supply tetraalkoxy titanium and aryl alcohol from the side part of a reaction distillation column.

The amount of the aryl alcohol added to the reaction distillation column is preferably added in an excessive amount relative to the tetraalkoxy titanium, and the molar ratio of the aryl alcohol and the tetraalkoxy titanium (for example, tetraisopropoxytitanium) to the titanium atom (mole number of aryl alcohol / titanium atoms) Molar number) is preferably 10 or more, more preferably 40 or more. 80 or less are preferable and, as for an upper limit, 60 or less are more preferable. That is, the molar ratio (mole number of aryl alcohols / mole number of titanium atoms) of the aryl alcohol and the titanium atom of tetraalkoxy titanium is preferably 10 to 80, more preferably 40 to 80, still more preferably 40 to 60, 30 To 50 are particularly preferred. If the molar ratio is small, the produced tetra (aryloxy) titanium may precipitate in the system and cause blockage, and when the molar ratio is large, the device tends to be larger than necessary for the tetra (aryloxy) titanium produced. have.

3-40 are preferable and, as for the reflux ratio of the column top part in reaction distillation which reacts tetraalkoxy titanium and an aryl alcohol, 5-20 are more preferable. If the reflux ratio is too low, there is a fear of lowering the conversion rate. Moreover, when the reflux ratio is 40 or more, the progress of the reaction is slowed.

In the reaction distillation column, it is preferable to continuously supply the tetraalkoxy titanium and the excess amount of the aryl alcohol to the reaction distillation column so that the molar ratio (aryl alcohol / titanium atom) between the titanium atom and the aryl alcohol is 40 to 80.

By supplying tetraalkoxy titanium and excess aryl alcohol to the reaction distillation column to react, extracting the oil containing the by-produced alkyl alcohol, and extracting the oil containing tetra (aryloxy) titanium and aryl alcohol from the bottom, It is preferable to obtain the aryl alcohol solution of tetra (aryloxy) titanium from which the by-produced alkyl alcohol was removed, and to supply it to a transesterification reaction process.

The reaction temperature in the reaction of tetraalkoxy titanium and aryl alcohol is preferably maintained at 160 to 300 ° C, more preferably 200 to 300 ° C. When reaction temperature is low, there exists a tendency for the conversion of tetraisopropoxytitanium to fall. When tetraphenoxytitanium is used as the tetra (aryloxy) titanium, obstruction may occur at the temperature below the melting point (153 ° C) of the tetraphenoxytitanium.

It is preferable to continuously extract tetra (aryloxy) titanium and arylalcohol from the bottom of the reaction distillation column, and to supply an arylalcohol solution of tetra (aryloxy) titanium which has been continuously removed by-product alkyl alcohol to the transesterification reaction step. .

The aryl alcohol solution of tetra (aryloxy) titanium obtained from the bottom of the reaction distillation column is supplied from the side of the reaction distillation column together with dialkyl oxalate and aryl alcohol without being isolated or purified from tetra (aryloxy) titanium, and alkyl oxalate. It is used as a catalyst in the transesterification reaction to produce aryl or diaryl oxalate. As a result, since the purification process of the catalyst can be greatly simplified, the environmental load due to the simplification of the manufacturing equipment, the reduction of the purification solvent, and the like, the reduction of the residence time by the simplified process, and the heat to the tetra (aryloxy) titanium Reduction of hysteresis, suppression of deterioration due to water of tetra (aryloxy) titanium and the like, and reduction of contact of the tetra (aryloxy) titanium with decomposable substances can be achieved. Improvement and reaction efficiency are improved.

[Material of apparatus]

In the method for producing a diaryl oxalate of the present invention, an apparatus (for example, a structure inside a distillation column such as a distillation column, a storage tank, an inner wall of a pipe, a tray, a packing material, etc.) in contact with a reaction solution of a transesterification reaction, and more specifically, an oxalic acid. The material of the diaryl purification column, the reaction vessel of the transesterification reaction or the reaction distillation column) is preferably an austenitic stainless steel containing 10 wt% or more of nickel and 1 to 4 wt% of molybdenum. In addition, it is preferable that the material of the apparatus is austenitic stainless steel substantially free of nitrogen atoms.

Among the austenitic stainless steels, austenitic stainless steels containing 16.00 to 18.00% by weight of chromium are preferable, and austenitic stainless steels containing substantially no nitrogen atoms are preferable. In addition, in this invention, an austenitic stainless steel which does not contain a nitrogen atom substantially refers to an austenitic stainless steel other than high nitrogen stainless steel by which nitrogen atom content is prescribed | regulated in JISG4304 etc.

Also, among austenitic stainless steels, SUS316 (Ni: 10.00 to 14.00 wt%, Cr: 16.00 to 18.00 wt%, Mo: 2.00 to 3.00 wt%, N: 0 wt%) or SUS316L (defined in JIS G 4304) Ni: 12.00 to 15.00 wt%, Cr: 16.00 to 18.00 wt%, Mo: 2.00 to 3.00 wt%, N: 0 wt%) are more preferred.

Carbon steel commonly used as a material of the device or SUS304 (Ni: 8.00 to 10.50 wt%, Cr: 18.00 to 20.00 wt%, Mo: 0 wt) in the portion in contact with the reaction solution of the transesterification reaction When using ordinary austenitic stainless steels, such as%, N: 0 weight%), corrosion, such as a decrease and discoloration of a surface, is observed, and long-term continuous operation becomes difficult.

[Production Method of Diaryl Oxalate]

Hereinafter, a method of producing a diaryl oxalate by providing an aryl alcohol solution of tetra (aryloxy) titanium as a catalyst will be described.

The method for producing diaryl oxalate includes a step of transesterifying a dialkyl oxalate and / or an alkyl oxalate with an aryl alcohol, and separating and recovering the obtained diaryl oxalate.

As a method of transesterification, the following methods are mentioned, for example.

The first method is a method for producing diaryl oxalate by transesterifying dialkyl oxalate and / or alkylaryl oxalate with aryl alcohol in the presence of an aryl alcohol solution of tetra (aryloxy) titanium as a catalyst.

In the second method, in the presence of an arylalcohol solution of tetra (aryloxy) titanium as a catalyst, dialkyl oxalate or alkylaryl oxalate is transesterified with arylalcohol while removing byproduct alkylalcohol to produce diaryl oxalate. That's how.

The third method involves transesterifying dialkyl oxalate and arylalcohol in the presence of an arylalcohol solution of tetra (aryloxy) titanium as a catalyst to produce alkylaryl oxalate, and then by-products in the presence of a transesterification catalyst It is a method of producing the diaryl oxalate by disproportionating reaction of alkylaryl oxalate, removing dialkyl oxalate.

In a fourth method, in the presence of an arylalcohol solution of tetra (aryloxy) titanium as a catalyst, dialkyl oxalate and arylalcohol are transesterified to produce alkylaryl oxalate while distilling off byproduct alkylalcohol, followed by esterification. It is a method of producing diaryl oxalate by performing reaction mainly having the heterogeneous reaction of alkylaryl oxalate, removing dialkyl oxalate and alkyl alcohol in presence of the catalyst to carry out exchange reaction. It is preferable to use a 4th method among these manufacturing methods.

In the manufacturing method of the diaryl oxalate, it demonstrates dividing into the (B-1) process, the (B-2) process, and the (B-3) process below.

In the alkylaryl oxalate production step (step (B-1)) of the present invention, alkylaryl oxalate can be produced, for example, in the following manner.

[(B-1) step]

Dialkyl oxalate produced in the step (A) is used in the alkylaryl oxalate production step (step (B-1)). In the step (B-1), a dialkyl oxalate, an aryl alcohol, and an aryl alcohol solution of tetra (aryloxy) titanium as a catalyst are supplied to a first reaction distillation column, whereby a first vapor containing alkyl alcohol as a main component is subjected to a first reaction. It is possible to produce alkylaryl oxalate by transesterifying dialkyl oxalate and aryl alcohol while extracting from the top of the distillation column.

As the first reaction distillation column, a multistage distillation column having a plurality of boranes can be used. In the first distillation column, in addition to the alkylaryl oxalate production step (step (B-1)), a heterogeneous reaction (diaryl oxalate production reaction, step (B-2)) is also performed at the same time.

In the step (B-1), an arylalcohol solution of dialkyl oxalate, arylalcohol, and tetra (aryloxy) titanium as a catalyst is placed in a region above the plurality of banded portions (or filler parts) of the first reaction distillation column. It is preferable to react, respectively supplying separately or in liquid mixture. Moreover, it is preferable to supply and react the reaction liquid extracted from the bottom part of a 1st reaction distillation column to the area | region of the upper part of a bandbed part (or a filler part) of a 2nd reaction distillation column.

In a 1st reaction distillation column, it is preferable to evaporate the 1st vapor containing the by-produced alkyl alcohol as a main component, and to extract it from the top of the 1st reaction distillation column. In addition, a cooler is installed in the extraction line connected to the top of the first reaction distillation column, and the first vapor is condensed to remove outside the reaction system of the transesterification reaction as a condensate mainly composed of alkyl alcohol. The low boiling point ether compound is contained in the condensate containing alkyl alcohol as a main component. The condensate containing alkyl alcohol as a main component is supplied to the (C) process for reducing the density | concentration of an ether compound.

[(B-2) step]

In the aryl oxalate production step ((B-2) step), for example, diaryl oxalate can be produced by the following method. The reaction liquid by transesterification reaction was taken out from the bottom of a 1st reaction distillation column, and it supplies to a 2nd reaction distillation column, and the 2nd vapor which contains dialkyl oxalate as a main component, and contains alkyl alcohol further has a part of the 2nd reaction distillation column It is preferable to carry out the disproportionation reaction of alkylaryl oxalate in presence of the aryl alcohol solution of tetra (aryloxy) titanium as a catalyst, extracting from this. It is preferable to distill off alkyl alcohol as needed, and to supply the 2nd vapor | steam extracted from the government part of a 2nd reaction distillation column, and to supply the oil component which has dialkyl oxalate and an aryl alcohol as a main component to a 1st reaction distillation column, and to reuse it.

The first and second reaction distillation columns are reaction distillation columns consisting of a distillation column having a plurality of boranes, or a reaction distillation column packed with a filler, and having a theoretical stage of at least two or more stages, and also 5 to 100 stages, especially 7 to 50 stages. It is preferable that it is a reaction distillation column. As a reaction distillation column of a multi-stage distillation column type, for example, a banded distillation column type using a bubble tray, a porous plate tray, a bubble tray, or the like, or filled with various fillers such as lashing rings, wrestling rings, and pollings. A packed distillation column type can be used, and a reactive distillation column having both a banding type and a packing type can also be used.

When the step of transesterifying is carried out in a liquid state while flowing the reaction liquid in the first and second reaction distillation columns, the reaction temperature is equal to or higher than the temperature at which the reaction liquid containing each raw material and the reaction product melts, Moreover, it is preferable that it is the temperature at which the alkyl oxalate and the aryl oxalate do not thermally decompose. It is preferable that this reaction temperature is about 50-350 degreeC, and also 100-300 degreeC, especially about 120-280 degreeC.

The pressure of the reaction in step (B-1) and step (B-2) may be any one of reduced pressure, atmospheric pressure, and pressurization, but the pressure and temperature at which the byproduct alkyl alcohol and dialkyl oxalate are distilled off may be used. It is preferable. For example, when reaction temperature is about 50-350 degreeC, it is preferable that reaction pressure is 0.01 mmHg-100 kg / cm <2> G, and it is more preferable that it is about 0.1 mmHg-50 kg / cm <2> G.

The reaction time (retention time of the reaction liquid in the first and second reaction distillation towers in the case of using a reaction distillation column consisting of a multi-stage distillation column) in the step of transesterification reaction is determined by the reaction conditions, the type and operation conditions of the reaction distillation column, and the like. Although it depends, for example, when reaction temperature is about 50-350 degreeC, it is preferable that it is about 0.01 to 50 hours, 0.02 to 10 hours, especially about 0.05 to 5 hours.

In addition, although the ratio of the dialkyl oxalate and aryl alcohol used in the (B-1) process and the (B-2) process changes with reaction conditions etc., it is 0.001-1000 with respect to the dialkyl oxalate to which aryl alcohol is supplied, for example. Preference is given to moles, more preferably from 0.1 to 100 moles, in particular from about 0.5 to about 20 moles. The amount of the arylalcohol solution of tetra (aryloxy) titanium as a catalyst used in the step of transesterification depends on the type and size of the reaction apparatus, the type and composition of the raw materials, and the reaction conditions. For example, oxalic acid It is preferable that it is about 0.0001 to 50 weight%, and also 0.001 to 30 weight%, especially about 0.005 to 10 weight%, expressed as a ratio with respect to the total amount of dialkyl and aryl alcohol.

[(B-3) step]

The reaction solution obtained in the step (B-1) and the step (B-2) is an arylalcohol solution of tetra (aryloxy) titanium as a raw material and a catalyst, alkylaryl oxalate of the reaction intermediate, diaryl oxalate of the target, alkylalcohol and It mainly contains dialkyl oxalate, and other by-products are very small. For this reason, the diaryl oxalate which is a target object can be easily isolate | separated and recovered from the reaction liquid obtained from a 2nd reaction distillation column, for example by normal distillation operation.

Specific examples of this separation and recovery include a method of separating and recovering diaryl oxalate by distillation and / or evaporation of a reaction liquid obtained by a transesterification reaction or the like with a distillation apparatus and / or an evaporation apparatus.

It is preferable to remove the titanium compound derived from tetra (aryloxy) titanium from the reaction liquid containing diaryl oxalate, and to make the density | concentration of the titanium compound of the reaction liquid containing diaryl oxalate be 10 weight ppm or less. . As a method of making the concentration of the titanium compound of the reaction liquid containing diaryl oxalate to 10 ppm by weight or less, for example, the reaction liquid obtained from the second reaction distillation column is supplied to a distiller or evaporator, and most of the reaction liquid is distilled. Or the method of removing a titanium type compound by evaporation is mentioned. At this time, most of the evaporated reaction solution may be supplied to a distillation column, and the diaryl oxalate may be purified in a step of distillation purification. It is preferable that it is 10 weight ppm or less, and, as for the density | concentration of the titanium compound in the reaction liquid containing diaryl oxalate, it is more preferable that it is 5 weight ppm or less.

The reaction liquid containing diaryl oxalate contains aryl alcohol, alkylaryl oxalate, etc. as an impurity.

However, since aryl alcohol and alkyl aryl oxalate have a large difference in boiling point from diaryl oxalate and are easily separated, even if distillation is carried out using a relatively low distillation column, for example, oxalic acid having a high purity of 97.0 wt% or more and 99.0 wt% or more Diaryl can be obtained.

When the obtained diaryl oxalate is used as a raw material of the diaryl carbonate, the purity of the diaryl oxalate is 97.0% by weight or more, but in particular, impurities (aryl alcohol, alkylaryl oxalate, etc.) are each 1.0% by weight or less, particularly 0.5% by weight. It is preferable that it is% or less and 0.1 weight% or less.

As impurities, in addition to aryl alcohol or alkyl oxalate, oxalic acid ester having at least one aryl ester group or a decomposition product thereof is a compound for fleece, a compound having a hydroxy group and an aryloxy group, or a hydroxy group and an aryloxy group of the compound Compounds reacted within or between molecules are included.

As a method of distilling-purifying aryl alcohol and alkyl oxalate contained as an impurity from the reaction liquid containing diaryl oxalate, the following methods which isolate | separate and collect | recover by classification are mentioned, for example.

The reaction liquid containing diaryl oxalate is supplied to a 1st reaction distillation column, and low vapor | steam (vapor containing alkylaryl oxalate and aryl alcohol) is extracted and condensed from the top part of a 1st reaction distillation column. Further, diaryl oxalate can be recovered by extracting the can liquid containing diaryl oxalate as a main component from the bottom of the first reaction distillation column and supplying it to the second reaction distillation column, and extracting the vapor of diaryl oxalate from the government of the second reaction distillation column. Can be. The condensate containing alkylaryl oxalate and aryl alcohol recovered from the government of the first reaction distillation column is preferably supplied to a step of transesterification reaction (step (B-1) or the like) and reused.

It is also possible to simplify the above-mentioned method and to separate and recover diaryl oxalate by fractionation using only the first distillation column. In this method, it is also possible to simplify and perform the above-mentioned separation and recovery only by the first reaction distillation column. For example, the evaporated fraction obtained by separating the titanium compound by an evaporator is supplied to the first reaction distillation column, and the vapor of low quality (alkylaryl oxalate and aryl alcohol) is extracted from the government, and cut again from the bottom of the distillation column. It can carry out by the method of recovering diaryl oxalate.

The concentration of the titanium compound in the reaction solution containing diaryl oxalate may be 10 ppm by weight or less, and the step of removing aryl alcohol and alkylaryl oxalate as impurities contained in the reaction solution may be performed.

For example, the reaction solution is first distilled in a first reaction distillation column to extract and remove low-quality steam (vapor containing alkylaryl oxalate and aryl alcohol) from the top of the first reaction distillation column, and at the same time, the first reaction distillation column. The can liquid containing diaryl oxalate as a main component was extracted from the bottom of the reaction mixture, and supplied to the second reaction distillation column, and then a can liquid containing a titanium compound was obtained from the bottom of the second reaction distillation column. The method of extracting and recovering the vapor of a diaryl is mentioned.

Further, the reaction solution was supplied to the first reaction distillation column to extract and remove a low quality vapor (steam containing alkylaryl oxalate and aryl alcohol) from the government of the first reaction distillation column, and then the vapor of diaryl oxalate was removed from the government. It can also extract and recover by distilling the vapor of diaryl oxalate by cooling, aggregating. Finally, the can solution containing the titanium compound can be removed from the bottom of the first reaction distillation column.

Among the methods for distilling aryl alcohol and alkylaryl oxalate to purify diaryl oxalate from the reaction solution described above, titanium compounds and the like are separated and the concentration of the titanium compound in the reaction solution containing diaryl oxalate is 10 ppm by weight. After making it below, it is preferable to use the method of distilling aryl alcohol and alkylaryl oxalate off and refine | purifying diaryl oxalate.

Purification of the reaction solution containing diaryl oxalate by distillation or the like in a state where the concentration of the titanium compound is high, furan compounds such as benzofuran-2,3-diones represented by the following general formula (1) which are colored substances by heating. This may be generated in turn. As benzofuran-2,3-dione, benzofuran-2,3-dione etc. are mentioned, for example.

Therefore, after lowering the concentration of the titanium compound in the reaction solution to 10 wt ppm or less, the reaction solution containing diaryl oxalate is distilled and purified to obtain a furan compound such as benzofuran-2,3-dione as a coloring component. The production of can be suppressed.

(Wherein R represents any one of a hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group, an aralkyl group, an aryl group, or a hydrogen atom or a halogen atom)

Among the furan compounds, benzofuran-2,3-diones, such as benzofuran-2,3-dione and alkyl-substituted benzofuran-2,3-dione, in particular, greatly influence the coloring of diaryl oxalate. For this reason, diaryl oxalate with little coloring can be obtained by suppressing the benzofuran-2,3-dione density | concentration in diaryl oxalate low.

Since the furan compound has a lower boiling point than the diaryl oxalate, even when the vapor of the diaryl oxalate is extracted from the distillation column, the furan-based compound generated in the can is accompanied by the vapor of the diaryl oxalate. In addition, even if it is going to extract the vapor of a furan type compound from the distillation column top part, since furan type compound is newly produced by heating can liquid, it is difficult to lower the concentration of furan type compound in diaryl oxalate.

Since it is not possible to purify to the state of high purity without coloring by distillation operation, it is important to make the titanium-type compound concentration in a liquid as low as possible at the time of distillation purification. Since the production rate of furan compounds such as benzofuran-2,3-dione is slow in the state where almost no titanium compound is contained, the diaryl oxalate and the furan compound can be easily separated by distillation.

As for the diaryl oxalate obtained by the manufacturing method of this invention, it is preferable that the density | concentration of the furan type compound contained in the diaryl oxalate is 500 ppm or less through the above-mentioned refinement | purification process etc. as needed.

The furan compound is a cause of coloring of the diaryl oxalate. For this reason, when the concentration of the furan-based compound contained in the diaryl oxalate is 500 ppm or less, diaryl oxalate having high transparency can be obtained.

It is preferable that it is 400 ppm or less, and, as for the density | concentration of the furan type compound contained in diaryl oxalate, it is more preferable that it is 300 ppm or less.

Examples of the furan compound include benzofuran-2,3-dione such as benzofuran-2,3-dione. In particular, benzofuran-2,3-dione is a large cause of coloring of diaryl oxalate. For this reason, the concentration of benzofuran-2,3-dione in diaryl oxalate is preferably 500 ppm or less, more preferably 400 ppm or less, and even more preferably 300 ppm or less.

In addition, the diaryl oxalate obtained by the production method of the present invention preferably has a melt haze color number of 200 or less at 150 ° C in air.

Diaryl oxalate is often used as a raw material of diaryl carbonate. If colored diaryl oxalate is used as a raw material, it becomes a cause of coloring of diaryl carbonate, which hinders the production of high purity diaryl carbonate. In the diaryl carbonate production step, furan compounds and the like in diaryl oxalate cause a high boiling point compound. For this reason, the presence of a large amount of furan compound in diaryl oxalate causes a decrease in selectivity and yield of diaryl carbonate in the diaryl carbonate production step.

[(C) step]

In this invention, the alkyl alcohol produced | generated by transesterification of dialkyl oxalate and an aryl alcohol in process (B-1) is collect | recovered, and it recycles to the process of producing dialkyl oxalate ((A) process). Impurities, such as low boiling ether compounds, are mixed in the alkyl alcohol, but among the various impurities, only the ether compound needs to reduce its concentration. This is because the yield and selectivity of the dialkyl oxalate are greatly reduced when the alkyl alcohol in which the ether compound is contained at a predetermined concentration or more is used in the step of producing dialkyl oxalate ((A) step). In the step (B-2), it is also preferable that the alkyl alcohol extracted as necessary from the second vapor extracted from the top of the second reaction distillation column also reduces the concentration of the low boiling point ether compound.

As an ether compound, alkylaryl ethers, such as anisole and dimethyl ether, and diphenyl ether are mentioned, for example. The content of the ether compound in the alkyl alcohol needs to be less than 1000 ppm by weight, particularly preferably 500 ppm by weight or less, more preferably 300 ppm by weight or less, and particularly preferably 100 ppm by weight or less. desirable. In particular, when the content of alkylaryl ethers such as anisole in the alkyl alcohol is large, the yield of dimethyl oxalate in the step (A) is lowered. Therefore, the content of alkylaryl ethers such as anisole in the alkyl alcohol is preferably reduced.

As a method of reducing the density | concentration of an ether compound in alkyl alcohol, the following method is mentioned, for example.

(B-1) if necessary, the vapor mainly containing alkyl alcohol extracted from the top of the first reaction distillation column in the step, and / or from the second steam extracted from the top of the second reaction distillation column in the step (B-2). By cooling and condensing the vapor containing the extracted alkyl alcohol, an alkyl alcohol containing a relatively high concentration of the ether compound is obtained. Alkyl alcohols containing a relatively high concentration of the ether compound can be distilled to separate the alkyl alcohol, thereby reducing the concentration of the ether compound.

[Manufacturing process of diaryl carbonate]

The obtained diaryl oxalate is decarbonylated to produce diaryl carbonate and carbon monoxide, and diaryl carbonate can be separated and recovered from the reaction mixture. This decarbonylation is preferably carried out in the liquid phase in the presence of a catalyst.

When decarbonylation of diaryl oxalate is carried out in a liquid phase, decarbonylation of diaryl oxalate can be carried out at a relatively low temperature (about 100 to 350 DEG C), and high selectivity (at least 50%) of diaryl carbonate. Above, especially the catalyst obtainable in 60 to 100%) is preferable.

As a catalyst used in a liquid phase reaction, the catalyst which consists of an organic phosphorus compound, Preferably, the organic phosphorus compound which has at least 1 carbon-phosphorus bond is mentioned, for example. As such an organophosphorus compound, at least 1 sort (s) chosen from phosphine (w), phosphine oxide (x), phosphine dihalide (y), and phosphonium salt (z) represented by Formula (w)-(z) The catalyst containing the organophosphorus compound of is mentioned preferably.

Wherein R ¹ to R ¹³ represent at least one group selected from an alkyl group having 1 to 16 carbon atoms, an aryl group having 6 to 16 carbon atoms, and an aralkyl group having 7 to 22 carbon atoms, and X can form a counter ion Y ¹ and Y ² each represent a halogen atom such as a chlorine atom, a bromine atom, an iodine atom, etc. Compounds (w) to (z) have at least one group as described above)

Examples of the group represented by R ¹ to R ¹³ include an alkyl group having 1 to 16 carbon atoms (methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, n-pentyl group, etc.). ), An aryl group having 6 to 16 carbon atoms (phenyl group, methylphenyl group, ethylphenyl group, methoxyphenyl group, ethoxyphenyl group, chlorophenyl group, fluorophenyl group, naphthyl group, methylnaphthyl group, methoxynaphthyl group, chloronaphthyl group, etc.) And aralkyl groups having 7 to 22 carbon atoms (benzyl group, phenethyl group, 4-methylbenzyl group, 4-methoxybenzyl group, p-methylphenethyl group and the like). An aryl group and an aralkyl group are substituents which directly bond with carbon forming the aromatic ring, and include an alkyl group having 1 to 16 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, a nitro group and a halogen atom (fluorine atom, chlorine atom, Bromine atom or the like).

Organophosphorus compounds (w) to (z) roneun, groups (R ¹ to R ¹³⁾ are both an aryl group is preferred, its 1 to 2 (especially 2) is an aryl date also, and the balance of an alkyl group, each having Or it may be an aralkyl group.

As a phosphine whose R <^1> -R <^3> of a formula (w) is all an aryl group, a triphenyl phosphine, a tris (4-chlorophenyl) phosphine, and a tris (4-tolyl) phosphine are mentioned, for example. Examples of the phosphine oxide in which R ⁴ to R ^{6 in} the formula (x) are all aryl groups include triphenylphosphine oxide, tris (4-chlorophenyl) phosphine oxide, and tris (4-tolyl) phosphine oxide. Can be mentioned.

Examples of the phosphine dihalide in which R ⁷ to R ⁹ in the formula (y) are all aryl groups include triphenylphosphine dichloride and triphenylphosphine dibromide. Among the phosphine dihalides, triaryl phosphine dichlorides such as triphenylphosphine dichloride are preferable.

A phosphonium salt of the formula (z) is R ¹⁰ to R ¹³ are are all aryl groups, plus counterion X ^- is a halogen ion, an aliphatic carboxylic acid ion or a borate ion or the like phosphonium salt is preferably fluoro, but R ¹⁰ 1-3, especially 2-3 of R <^13> are an aryl group, remainder is an aralkyl group or an alkyl group, and the counter ion X <^-> may be a halogen ion, an aliphatic carboxylic acid ion, or a fluoroborate ion. As a phosphonium salt whose R <^10> -R <^13> of formula (z) is an aryl group, all, for example, tetraphenyl phosphonium chloride, tetraphenyl phosphonium bromide, 4-chlorophenyl triphenyl phosphonium chloride, 4-chlorophenyl tri Relative ion X, such as phenyl phosphonium bromide, 4-ethoxy phenyl triphenyl phosphonium chloride, 4-ethoxy phenyl triphenyl phosphonium bromide, 4-methylphenyl triphenyl phosphonium chloride, 4-methylphenyl triphenyl phosphonium bromide, etc. ^The phosphonium salt whose ^- is a halogen ion is mentioned.

Among the organophosphorus compounds, tetraarylphosphonium salts are preferred. Among these, tetraaryl phosphonium halide is more preferable, but tetraaryl phosphonium chloride such as tetraphenyl phosphonium chloride is particularly preferable. The decarbonylation catalyst containing the organophosphorus compound may be used alone, or may be a mixture of two or more kinds, and may be further dissolved and / or suspended uniformly in the reaction solution. It is preferable that the quantity of the organophosphorus compound used at a decarbonyl process is about 0.001-50 mol% with respect to diaryl oxalate, and it is about 0.01-20 mol%.

It is preferable that at least 1 type of inorganic or organic halogen compound type additive is added to the decarbonylation catalyst which consists of organophosphorus compounds as needed. When using a phosphine or a phosphine oxide as an organophosphorus compound, or when using phosphonium salts other than a halide and a hydrogen dihalide, it is preferable to add this halogen compound additive. It is preferable that the quantity of the halogen compound type additive added is about 0.01-150 times mole with respect to an organophosphorus compound, and also about 0.05-100 times mole.

Examples of the inorganic halogen compound additives include halides of aluminum (aluminum chloride, aluminum bromide), halides of platinum group metals (platinum chloride, ruthenium chloride, palladium chloride, etc.), halides of phosphorus (such as phosphorus pentachloride), Sulfur halides (such as thionyl chloride), hydrogen halides (such as hydrogen chloride), and halogens such as chlorine. As the organic halogen compound additive, for example, a structure (C-Hal) in which a halogen atom is bonded to saturated carbon, or a structure (CO-Hal) in which a halogen atom is bonded to carbonyl carbon is preferable. Do. As such an organic halogen compound additive, for example, alkyl halide (chloroform, carbon tetrachloride, 1,2-dichloroethane, alkyl chloride such as butyl chloride), aralkyl halide (aralkyl chloride such as benzyl chloride), halogen Substituted aliphatic carboxylic acid (chloroacetic acid, bromoacetic acid, etc.), acid halide (acid chlorides, such as oxalyl chloride, propionyl chloride, benzoyl chloride, etc.) are mentioned. However, Hal represents halogen atoms, such as a chlorine atom and a bromine atom.

Decarbonylation of diaryl oxalate is obtained by supplying diaryl oxalate to a reactor in which a catalyst (and optionally a halogen compound additive) mainly containing an organic phosphorus compound is present, and removing carbon monoxide generated. Preferably, the reel is decarbonylated in the liquid phase to produce diaryl carbonate. At this time, it is preferable that reaction temperature is 100-450 degreeC, and also 160-400 degreeC, especially 180-350 degreeC. In addition, the reaction pressure is not particularly limited and may be, for example, in the range of 10 mmHg to 10 kg / cm 2 G. However, the carbon monoxide produced in the decarbonylation step is subjected to alkali treatment and then supplied to the methyl nitrite regeneration step. It is preferable that it is the range of 10 kg / cm <2> G from normal pressure, and 5 kg / cm <2> G from normal pressure, especially 2-5 kg / cm <2> G. Although no special solvent is required for the reaction, aprotic solvents such as diphenyl ether, sulfolane, N-methylpyrrolidone, and dimethyl imidazolidone may be used as necessary.

As the reactor in decarbonylation, any type of reactor can be used as long as it can decarbonylate diaryl oxalate in the presence of an organophosphorus compound to produce diaryl carbonate together with carbon monoxide. For example, when the decarbonylation of diaryl oxalate is performed in the liquid phase, a single tank or a multi-tank completely mixed reactor (stirrer), a tower reactor, or the like can be used. The material of the reactor is not particularly limited as long as it has sufficient heat resistance in decarbonylation of diaryl oxalate. For example, glass, stainless steel (SUS), aluminum alloy, nickel alloy and the like are suitably used.

Since the reaction solution obtained by decarbonylation of diaryl oxalate contains unreacted diaryl oxalate or organophosphorus compound, in order to separate and recover the diaryl carbonate from the reaction solution, a distillation film evaporator, a thin film evaporator, or the like is used. After the catalyst is separated and recovered by an evaporation apparatus, a method of distilling the evaporated fraction using a distillation apparatus such as a packed column or a bedside column having a certain number of theoretical stages (particularly 5 to 50 stages) is preferably used. The reaction solution is distilled by a distillation apparatus such as a packed column or a bedside column to extract diaryl carbonate from the tower portion, and to extract a can solution containing unreacted diaryl oxalate or organophosphorus compound from the bottom of the column. The method is also used. The extracted liquid can be circulated to the reactor of the decarbonyl reaction. In this way, the diaryl carbonate can be separated and recovered from the reaction solution to obtain a high purity diaryl carbonate.

[Production Method of Polycarbonate]

Diaryl carbonate prepared can be reacted with bisphenol A in the presence of a basic alkali metal salt to obtain polycarbonate.

Examples of basic alkali metal salts include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium bicarbonate, potassium hydrogencarbonate, lithium bicarbonate, cesium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate and acetic acid Sodium, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium borohydride, phenylated Potassium boron, lithium phenyl boride, cesium borohydride, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, sodium hydrogen phosphate, potassium dihydrogen phosphate, lithium lithium phosphate, sodium cesium phosphate, sodium phenyl phosphate, Diphenyl potassium phosphate, diphenyl lithium phosphate, diphenyl cesium phosphate, sodium, potassium, lithium, cesium alcoholate, phenolate, disodium salt of bisphenol A, dipotassium salt , Lithium lithium salts, cesium salts, and the like.

It does not restrict | limit especially as addition amount of basic alkali metal salt, For example, it can use in the range of 1 * 10 <^-9> -1 * 10 <^-3> mol with respect to 1 mol of bisphenol A. As an alkali metal compound which is especially favorable in terms of physical properties and handling, the amount of basic alkali metal salt added is preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻⁵ moles with respect to 1 mole of bisphenol A, particularly preferably 2 ×. It is the range of 10 <^{-8> -8} * 10 <^-6> moles. If the amount of addition of the basic alkali metal salt is too small, the required polymerization activity tends not to be obtained. If the amount of addition is too large, the polymer color deteriorates and the branching tends to increase.

It is also possible to use together basic compounds, such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound, as an auxiliary catalyst with basic alkali metal salt.

Specific examples of the basic boron compound include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron and triethylphenylboron And hydroxides such as tributyl benzyl boron, tributyl phenyl boron, tetraphenyl boron, benzyl triphenyl boron, methyl triphenyl boron and butyl triphenyl boron.

Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, or quaternary phosphate. Phosphium salts; and the like.

As a basic ammonium compound, For example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzyl ammonium hydroxide , Trimethylphenylammonium hydroxide, triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenyl Ammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide, butyltriphenylammonium hydroxide and the like.

Examples of the amine compound include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4 -Methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.

As a manufacturing method of polycarbonate which makes manufactured diaryl carbonate react with bisphenol A in presence of basic alkali metal salt, the following methods are mentioned, for example.

Diphenyl carbonate 1.07 is mixed with bisphenol A 1 at molar ratio, and it is maintained at 130 degreeC, and 1 ml of 0.01 N sodium hydroxide (1 micromole with respect to 1 mol of bisphenol A) is used as a catalyst for this mixed melt. When the polycondensation reaction was carried out while distilling off the phenol produced by distilling off at a temperature of 210 ° C./100 mmHg for 60 minutes, 240 ° C./15 mmHg for 60 minutes, and 280 ° C./0.5 mmHg for 2 hours at any time, an aromatic having a viscosity average molecular weight of 20,000 was obtained. Polycarbonate is obtained and can be cut into cutters to form pellets.

[Example]

Hereinafter, an Example demonstrates this invention in detail. However, the present invention is not limited at all by the following examples.

&Lt; Synthesis Example 1 &

Synthesis of Tetraphenoxycitane

300 ml of phenol was put into the bottom of the inner diameter 32 mm and the Aldersho type reaction distillation column (hereinafter called "reaction distillation column for catalyst synthesis") provided with a 1 L volume bottom flask, and it heated up by the oil bath. After the temperature distribution in the reaction distillation column for catalyst synthesis was stabilized while maintaining the conversion flow state, phenol was fed at 342.4 g / h and tetraisopropoxytitanium (TIPT) at a flow rate of 21.6 g / h. The ratio (phenol / Ti) between the number of moles of phenol fed and the number of moles of Ti atoms in TIPT was 48. The effluent from the saw was taken out while maintaining the reflux ratio at 5. In addition, the bottom was continuously extracted from the bottom of the reaction distillation column for catalyst synthesis so that the liquid level was maintained at 330 ml. The bottom liquid was analyzed until it reached a steady state in this state. As a result, 10.8 wt% of tetraphenoxycitane (TPT), 89.2 wt% of phenol, and 114 ppm of isopropanol (IPA) were detected. Moreover, the effluent liquid composition was 71.8 weight% of phenols, and 28.2 weight% of isopropanol. The extraction amount at that time was 295.4 g / h of bottom liquid, and 68.6 g / h of top discharge liquid. Moreover, bottom temperature was 190 degreeC and top temperature was 164 degreeC. As a result, the conversion rate (TPT yield) of TIPT to TPT was 99.8%. The reaction conditions and results are shown in Table 1 below.

In addition, TIPT conversion was calculated | required by the following formula.

<Synthesis Examples 2 to 4>

Synthesis of Tetraphenoxycitane

The same experiment as in Synthesis example 1 is shown in Table 1, with the result of changing some conditions as shown in Table 1.

The reaction solution of Synthesis Example 4 partially precipitated TPT.

&Lt; Synthesis Example 5 &

Tetraphenoxycitane was synthesized in the same manner as in Synthesis example 1 except that tetraisopropoxycitane was fed to the bottom. As a result, the conversion rate (TPT yield) of TIPT to TPT was 93.1%.

&Lt; Example 1 >

A mixture of phenol (PhOH) and dimethyl oxalate (DMO) at the bottom of an Aldersho type reaction distillation column (32 mm inner diameter, 50 stages of actual number, hereinafter referred to as "first reaction distillation column") equipped with a 1 L volume bottom flask 300 ml of (PhOH / DMO molar ratio 2/1) was added thereto, followed by heating with an oil bath to react. As soon as it was stabilized by the conversion flow, a bottom liquid extracted from the bottom of the reaction distillation column for the synthesis of catalyst of Synthesis Example 1 was supplied with 300 ml / h of a mixture solution of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the top of the column. Phenol solution of TPT) was fed at 9 ml / h. As soon as methanol began to flow out from the saw, extraction was started at a reflux ratio of 2. The bottom liquid was also continuously discharged to maintain 300 ml of liquid level.

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the column was stabilized (5 hours after the start of supply), and 6.75% by weight of diphenyl oxalate, 26.77% by weight of methyl phenyl oxalate, 23.23% by weight of dimethyl oxalate, and 42.91% by weight of phenol. It was. In addition, the extraction liquid from the top was 99.7 weight% of methanol, and 0.3weight% of dimethyl oxalate.

<Example 2>

300 ml of a mixed solution (PhOH / DMO molar ratio 2/1) of phenol (PhOH) and dimethyl oxalate (DMO) was added to a bottom flask of a first reaction distillation column, and heated and reacted with an oil bath. As soon as it was stabilized by the conversion flow, a bottom liquid extracted from the bottom of the reaction distillation column for synthesizing catalyst of Synthesis Example 2 was supplied with 300 ml / hr of a mixture of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the top of the column. Phenol solution of TPT) was fed at 9 ml / h. As soon as methanol began to flow out from the saw, extraction was started at a reflux ratio of 2. The bottom liquid was also continuously discharged to maintain 300 ml of liquid level.

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the tower was stabilized (5 hours after the start of supply), and 6.72% by weight of diphenyl oxalate, 26.80% by weight of methyl phenyl oxalate, 23.20% by weight of dimethyl oxalate, and 42.94% by weight of phenol. It was. In addition, the extraction liquid from the top was 99.7 weight% of methanol, and 0.3weight% of dimethyl oxalate.

<Example 3>

300 ml of a mixed solution (PhOH / DMO molar ratio 2/1) of phenol (PhOH) and dimethyl oxalate (DMO) was added to a bottom flask of a first reaction distillation column, and heated and reacted with an oil bath. As soon as it was stabilized by the conversion flow, a bottom liquid extracted from the bottom of the reaction distillation column for synthesizing catalyst of Synthesis Example 2 was supplied with 300 ml / hr of a mixture of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the top of the column. Phenol solution of TPT) was fed at 9 ml / h. As soon as methanol began to flow out from the saw, extraction was started at a reflux ratio of 2. The bottom liquid was also continuously discharged to maintain 300 ml of liquid level.

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the column was stabilized (5 hours after the start of supply), and 6.68 wt% diphenyl oxalate, 26.82 wt% methyl oxalate, 23.25 wt% dimethyl oxalate, and 42.91 wt% phenol It was. In addition, the extraction liquid from the top was 99.7 weight% of methanol, and 0.3weight% of dimethyl oxalate.

<Example 4>

300 ml of a mixed solution (PhOH / DMO molar ratio 2/1) of phenol (PhOH) and dimethyl oxalate (DMO) was added to a bottom flask of a first reaction distillation column, and heated and reacted with an oil bath. As soon as it was stabilized by the conversion flow, a bottom liquid extracted from the bottom of the reaction distillation column for synthesizing catalyst of Synthesis Example 2 was supplied with 300 ml / hr of a mixture of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the top of the column. Phenol solution of TPT) was fed at 9 ml / h. As soon as methanol began to flow out from the saw, extraction was started at a reflux ratio of 2. The bottom liquid was also continuously discharged to maintain 300 ml of liquid level.

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the tower was stabilized (5 hours after the start of supply), and 6.70% by weight of diphenyl oxalate, 26.84% by weight of methyl phenyl oxalate, 23.25% by weight of dimethyl oxalate, and 42.91% by weight of phenol. It was. In addition, the extraction liquid from the top was 99.7 weight% of methanol, and 0.3weight% of dimethyl oxalate.

<Example 5>

300 ml of a mixed solution (PhOH / DMO molar ratio 2/1) of phenol (PhOH) and dimethyl oxalate (DMO) was added to a bottom flask of a first reaction distillation column, and heated and reacted with an oil bath. As soon as it was stabilized by the conversion flow, a bottom liquid extracted from the bottom of the reaction distillation column for synthesizing catalyst of Synthesis Example 2 was supplied with 300 ml / hr of a mixture of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the top of the column. Phenol solution of TPT) was fed at 9 ml / h. As soon as methanol began to flow out from the saw, extraction was started at a reflux ratio of 2. The bottom liquid was also continuously discharged to maintain 300 ml of liquid level.

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the tower was stabilized (5 hours after the start of supply), and 5.40% by weight of diphenyl oxalate, 27.34% by weight of methyl phenyl oxalate, 24.01% by weight of dimethyl oxalate, and 42.95% by weight of phenol. It was. In addition, the extraction liquid from the top was 99.7 weight% of methanol, and 0.3weight% of dimethyl oxalate.

&Lt; Comparative Example 1 &

The transesterification reaction of phenol and dimethyl oxalate was carried out in the same manner as in Example 1 except that 7.6 wt% TIPT phenol solution was fed at 8.5 ml / h instead of the phenol solution of TPT obtained in Synthesis Example 1. .

The composition of the bottom liquid was analyzed by gas chromatograph at the time when the state of the tower was stabilized (5 hours after the start of supply), and 6.63% by weight of diphenyl oxalate, 26.33% by weight of methyl phenyl oxalate, 23.48% by weight of dimethyl oxalate, and 43.38% by weight of phenol In addition, traces of peaks of isopropyl oxalate and methyl isopropyl oxalate were detected. In addition, the extraction liquid (about 25 ml / h) from the top was 98.4 weight% of methanol, 1.4 weight% of isopropanol, and 0.2 weight% of dimethyl oxalate.

<Example 6>

The bottom liquid extracted from the bottom of the reaction distillation column for catalyst synthesis of Synthesis Example 1 was supplied with 330 g / h of a mixed liquid of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the upper part of the Alder Show of the first reaction distillation column. Phenol solution of TPT) was supplied at 9 ml / h. The bottom flask was heated to 190 ° C, and the transesterification reaction was carried out while condensing the vapor from the tower top with a cooler and extracting it at reflux ratio 2. The composition of the column bottom liquid (reaction liquid) was analyzed by gas chromatography at the time when the state of the column was stabilized (5 hours after the start of supply). Diphenyl oxalate, 6.74 wt%, methylphenyl oxalate, 26.76 wt%, and dimethyl oxalate 23.45 wt% And phenol was 42.62% by weight. In addition, the extraction amount of the column bottom liquid was about 306 g / h. In the column top, a liquid having a composition of 99.7% by weight of methanol and 0.3% by weight of dimethyl oxalate was extracted at about 24 g / h.

As a 2nd reaction distillation column, the reaction liquid after the said transesterification reaction was supplied at 300 ml / h in the 12th stage from the top of this 2nd reaction distillation column using the Aldersho type reaction distillation column of the same type as the 1st reaction distillation column. The bottom flask was heated to 230 ° C. with a mantle heater, and the vapor from the tower was condensed with a cooler, followed by discharging without reflux, to perform a disproportionation reaction. The composition of the column bottom liquid (reaction liquid) was analyzed by gas chromatography at the time when the state of the column became stable (5 hours after the start of supply). Diphenyl oxalate 53.22 wt%, methylphenyl oxalate 25.81 wt% and dimethyl oxalate 2.37 wt% And phenol was 17.14 wt%. In addition, the extraction amount of the column bottom liquid was about 132 g / h. From the tower, a liquid having a composition of 2.32% by weight of methanol, 43.75% by weight of dimethyl oxalate, 50.16% by weight of phenol, 3.64% by weight of methyl phenyl oxalate, and 0.13% by weight of diphenyl oxalate was extracted at about 189 g / h.

The tower bottom liquid (reaction liquid) obtained above was supplied at 100 ml / h to the rotary thin film type | mold evaporator (heating area: 0.1 m <2>) reduced by the pressure of 20 mmHg, and the oxalic acid was continuously heated by heating the evaporator to 200 degreeC with a heating medium. Dimethyl, phenol, methylphenyl oxalate and dimethyl oxalate were evaporated and condensed with a cooler. At the bottom of the evaporator, a liquid containing about 20% by weight of tetraphenoxycitane was extracted at about 7 g / h.

In addition, the piping from the vapor | evapor outlet of a thin film evaporator to a cooler is called a rising pipe, and the demister was provided in the rising piping part of an evaporator and a cooler.

The whole condensate was supplied from the upper part of this tower using the glass distillation tower of 20 mm inside diameter and 2 m high which filled the helipack (5 * 5 mm). Continuous distillation was performed at a can liquid temperature of 135 ° C., a column pressure of 10 mmHg, and a reflux ratio of 2, and a liquid having a composition of 6.52% by weight of dimethyl oxalate, 31.50% by weight of phenol, and 61.95% by weight of methyl phenyl oxalate was extracted at 43 ml / h from the tower portion. Diphenyl oxalate with a purity of 99.6% by weight was extracted from the bottom of the column at about 50 g / h. The titanium concentration contained in the liquid extracted from the column bottom was 2.5 ppm by weight based on the ICP measurement.

In the obtained oxalic acid diphenyl, as a furan compound, 20 ppm of benzo-2,3-dione was contained and the molten haze color number was 100.

&Lt; Example 7 >

Using a glass distillation column having an inner diameter of 20 mm and a height of 2 m filled with a helipak (5 × 5 mm), 100 ml / of the column bottom liquid obtained in Example 6 (purity 99.6 wt% diphenyl oxalate) was obtained from the top of the tower. fed in h. Distillation was performed continuously by the can liquid temperature of 178 degreeC, column top pressure 10mmHg, and reflux ratio 2. The liquid of 99.9 weight% of diphenyl oxalate compositions was extracted from the tower | column at about 98 g / h. At the bottom of the column, a liquid containing fertilizer was extracted at about 7 g / h. Diphenyl oxalate obtained contained 80 ppm of benzofuran-2,3-dione other than 0.02 weight% of phenols and 30 ppm of methylphenyl oxalate as an impurity, and melted haze color number was 100.

&Lt; Example 8 >

Synthesis of Diphenylcarbonate

1.5 mol% of tetraphenylphosphonium chloride was added to the diphenyl oxalate obtained in Example 6, and it heated and dissolved at 150 degreeC. The solution was supplied to a device in which two glass reactors (inner volume 1 L) equipped with a thermometer, a stirrer and an overflow tube were supplied at 300 ml / h using a metering pump, and the two reactors were used as a mantle heater. It heated and maintained at 230 degreeC, and the decarbonyl reaction of diphenyl oxalate was performed. In addition, the overflow position of each reactor was 600 mL. The obtained reaction liquid was refine | purified by distillation under reduced pressure, and diphenyl carbonate was obtained.

&Lt; Example 9 >

The bottom liquid extracted from the bottom of the reaction distillation column for catalyst synthesis of Synthesis Example 1 was supplied with 330 g / h of a mixed liquid of 61.4% by weight of phenol and 38.6% by weight of dimethyl oxalate from the upper part of the Alder Show of the first reaction distillation column. Phenol solution of TPT) was supplied at 9 ml / h. The bottom flask was heated to 190 ° C, and the transesterification reaction was carried out while condensing the vapor from the tower top with a cooler and extracting it at reflux ratio 2. The composition of the column bottom liquid (reaction liquid) was analyzed by gas chromatography at the time when the state of the column was stabilized (5 hours after the start of supply). Diphenyl oxalate, 6.74 wt%, methylphenyl oxalate, 26.76 wt%, and dimethyl oxalate 23.45 wt% And phenol was 42.62% by weight. In addition, the extraction amount of the column bottom liquid was about 306 g / h. In the column top, a liquid having a composition of 99.7% by weight of methanol and 0.3% by weight of dimethyl oxalate was extracted at about 24 g / h.

As a 2nd reaction distillation column, the reaction liquid after the said transesterification reaction was supplied at 300 ml / h in the 12th stage from the top of this 2nd reaction distillation column using the Aldersho type reaction distillation column of the same type as the 1st reaction distillation column. The bottom flask was heated to 230 ° C. with a mantle heater, and condensation of the vapor from the tower was carried out with a cooler, followed by extraction without reflux, to perform a disproportionation reaction. The composition of the column bottom liquid (reaction liquid) was analyzed by gas chromatography at the time when the state of the column became stable (5 hours after the start of supply). Diphenyl oxalate 53.22 wt%, methylphenyl oxalate 25.81 wt% and dimethyl oxalate 2.37 wt% And phenol was 17.14 wt%. In addition, the extraction amount of the column bottom liquid was about 132 g / h. From the tower, a liquid having a composition of 2.32% by weight of methanol, 43.75% by weight of dimethyl oxalate, 50.16% by weight of phenol, 3.64% by weight of methyl phenyl oxalate, and 0.13% by weight of diphenyl oxalate was extracted at about 189 g / h.

The tower bottom liquid (reaction liquid) obtained above was supplied at 100 ml / h to the rotary thin film type | mold evaporator (heating area: 0.1 m <2>) reduced by the pressure of 20 mmHg, and the oxalic acid was continuously heated by heating the evaporator to 200 degreeC with a heating medium. Dimethyl, phenol, methylphenyl oxalate and dimethyl oxalate were evaporated and condensed with a cooler. At the bottom of the evaporator, a liquid containing about 20% by weight of tetraphenoxycitane was extracted at about 7 g / h.

In addition, the piping from the vapor | evapor outlet of a thin film evaporator to a cooler is called a horizontal piping, and a demister is not provided.

Moreover, the whole condensate liquid was supplied from the upper part of this tower using the glass distillation column of the inner diameter of 20 mm and height of 2 m which filled the helipack (5x5 mm). Continuous distillation was carried out at a bottom temperature of 135 ° C., a column pressure of 10 mmHg, and a reflux ratio of 2, and a liquid having a composition of 6.51% by weight of dimethyl oxalate, 31.57% by weight of phenol, and 61.83% by weight of methyl phenyl oxalate was extracted at 43 ml / h from the top portion, Diphenyl oxalate with a purity of 99.5% by weight was extracted from the bottom of the column at about 50 g / h. The titanium concentration contained in the liquid extracted from the column bottom was 38 ppm by weight based on ICP.

In the obtained diaryl oxalate, 100 ppm of benzofuran-2,3-dione was contained as a furan compound, and the molten haze color number was 500.

&Lt; Example 10 >

Distillation purification was carried out in the same manner as in Example 7, except that the column bottom liquid obtained in Example 9 was used. A liquid having a composition of 99.9% by weight of diphenyl oxalate was extracted from the tower portion at about 98 g / h. At the bottom of the column, a liquid containing fertilizer was extracted at about 7 g / h. The obtained diphenyl oxalate contained 760 ppm of benzofuran-2,3-dione in addition to 0.04 weight% of phenols and 30 ppm of methylphenyl oxalate as an impurity, and melted haze color number was 400.

<Example 11>

A mixed solution containing 50.4% by weight of phenol, 42.1% by weight of dimethyl oxalate, 3.2% by weight of methyl phenyl oxalate, and the like was supplied between the distillation part and the reaction part of the distillation column of the first reaction distillation column at 261.5 kg / h. The bottom liquid (phenol solution of TTP) extracted from the bottom of the reaction distillation column for catalyst synthesis thus obtained was supplied at 1.3 kg / h. The temperature of the tower bottom was heated to 210 degreeC, adjusting the pressure of the tower top part to 0.07 MPaG. The steam from the tower top was condensed with a cooler and discharged at a reflux ratio 4, and the tower bottom liquid was continuously discharged to keep the liquid level constant. At this time, the composition of the column top liquid was 98.4 wt% of methanol, 0.8 wt% of dimethyl oxalate, and the like, and the extraction amount was 12.8 kg / h. The composition of the column bottom liquid was 27.5 weight% of dimethyl oxalate, 38.4 weight% of phenol, 26.5 weight% of methyl phenyl oxalate, 5.6 weight% of diphenyl oxalate, etc., and extraction amount was 250.0 kg / h.

As the second reaction distillation column, a column bottom liquid of the first reaction distillation column was supplied to the top of the second reaction distillation column at 250.0 kg / h using a reaction distillation column having a band end portion, and further, a column of the second distillation column which is a subsequent step. While the semen was supplied to the bottom of the second reaction distillation column at 28.4 kg / h, the temperature of the tower bottom was heated to 200 ° C. while adjusting the pressure of the tower to 191 Torr. The steam from the tower part was condensed by a cooler and extracted in its entirety, and the tower bottom liquid was continuously extracted to maintain a constant liquid amount, and a heterogeneous reaction was performed. At this time, the composition of the column top liquid was 45.5% by weight of dimethyl oxalate, 49.7% by weight of phenol, 4.3% by weight of methyl phenyl oxalate, and the like, and its extraction amount was 190.3 kg / h, and was recycled to the first reaction distillation column. The extraction amount at the bottom of the column was 88.1 kg / h, and the composition was 62.5 weight% of diphenyl oxalate, 24.3 weight% of methyl phenyl oxalate, 2.1 weight% of dimethyl oxalate, 5.2 weight% of phenol, and others.

The bottom liquid of the second reaction distillation column was fed to the falling film type evaporator at 88.1 kg / h, and the effluent was extracted at 74.9 kg / h while adjusting the pressure to 23 Torr. The composition was 63.3 weight% of diphenyl oxalate, 28.1 weight% of methylphenyl oxalate, 6.0 weight% of phenols, 2.4 weight% of dimethyl oxalate, and others. The composition of the can solution includes 58.0% by weight of diphenyl oxalate, 2.5% by weight of methylphenyl oxalate, 10.0% by weight of tetraphenoxycitane, and others, purging 1.0 kg / h, and the remaining 12.2 kg / h is the first reaction distillation column. Recycled.

The effluent from the falling film type evaporator was fed to the first reaction distillation column at 74.9 kg / h. The temperature of the column bottom liquid was heated to 218 ° C. while preparing the pressure of the column to 20 Torr. The steam from the tower part was condensed with a cooler, extracted at a reflux ratio of 0.5, and recycled to 28.4 kg / h in a second reaction distillation column. The composition was 74.1 kg / h of methyl phenyl oxalate, 16.0 kg / h of phenol, 6.4 weight% of dimethyl oxalate, 3.6 weight% of diphenyl oxalate, and others. The extraction amount at the bottom of the column was 46.5 kg / h, and the composition thereof was 99.8% by weight of diphenyl oxalate, and the like.

The temperature of the column bottom was heated to 230 degreeC, supplying the column bottom liquid of a 1st distillation column to a 2nd distillation column, and adjusting the pressure of a tower | column part to 15 Torr. The steam from the tower part was condensed by a cooler and extracted at a reflux ratio 5, and the column bottom liquid was continuously discharged to keep the temperature constant. At this time, the composition of the column top liquid was 99.9% by weight of diphenyl oxalate, and the like, and the amount of extraction was 46.2 kg / h. The extraction amount at the bottom of the column was 0.3 kg / h, and the composition was 75.9% by weight of diphenyl oxalate, and the like.

The material of the contact part of the said equipment, ie, the 1st reaction distillation column, the 2nd reaction distillation column, the falling film type | mold evaporator, the 1st distillation column, and the 2nd distillation column was SUS316L. The surface observation (SEM) and the histological examination (SUMP) were performed inside after 8000 hours (h), but the abnormality in each location and a problem was not recognized.

<Evaluation 1>

In Example 11, a test piece of SUS316L is provided at the bottom of the first reaction distillation column, the bottom of the second reaction distillation column, the bottom of the first distillation column, and the bottom of the second distillation column, and after 8000 h has elapsed, the test piece is taken out to corrode from the weight change. The rate was calculated. The results are shown in Table 2 below.

<Evaluation 2>

In Example 11, a test piece of SUS316 is provided at the bottom of the first reaction distillation column, the bottom of the second reaction distillation column, the bottom of the first distillation column, and the bottom of the second distillation column, and the test piece is taken out after 8000 h. The rate was calculated. The results are shown in Table 3 below.

<Evaluation 3>

In Example 11, a test piece of SUS304 is provided at the bottom of the first reaction distillation column, the bottom of the second reaction distillation column, the bottom of the first distillation column, and the bottom of the second distillation column, and after 8000 h has elapsed, the test piece is taken out to corrode from the weight change. The rate was calculated. The results are shown in Table 4 below.

<Evaluation 4 to 14>

In the evaluation 3, the test pieces shown in Table 4 were arrange | positioned at the bottom of the 1st reaction distillation column which had the highest corrosion rate, and after 8000 h passed, each test piece was taken out and external appearance observation was performed.

What was considered to be a result equivalent to the external appearance of the test piece after the test of evaluation 1 was evaluated as "(circle)", and what was considered to be corroded more clearly than the external appearance of the test piece after the test of evaluation 1 was evaluated as "x".

The chemical composition of the steel used in the evaluations 4-14 is also shown in Table 5 below.

&Lt; Example 12 >

Synthesis of Diphenylcarbonate

Tetraphenylphosphonium chloride was added 1.5 mol% to diphenyl oxalate (purity 99.9 weight%) obtained in Example 11, and it heated and melt | dissolved at 150 degreeC. The solution was supplied to a device in which two glass reactors (inner volume 1 L) equipped with a thermometer, a stirrer and an overflow tube were supplied at 300 ml / h using a metering pump, and the two reactors were used as a mantle heater. It heated and maintained at 230 degreeC, and the decarbonyl reaction of diphenyl oxalate was performed. In addition, the overflow position of each reactor was 600 mL. The obtained reaction liquid was refine | purified by distillation under reduced pressure, and diphenyl carbonate was obtained.

&Lt; Example 13 >

Synthesis of Polycarbonate Resin

Bisphenol A and diphenyl carbonate obtained in Example 12 were mixed at a molar ratio of 1: 1.07, and kept at 130 ° C. for 24 hours to obtain a mixed melt. To the obtained mixed melt, 1 μmol of 0.01 N sodium hydroxide was added as a catalyst to 1 mol of bisphenol A under a nitrogen atmosphere, 60 minutes at 210 ° C / 100 mmHg, 60 minutes at 240 ° C / 15 mmHg, and 280 ° C / 0.5 mmHg. The polycondensation reaction was performed, distilling a phenol byproduct | produced by distillation for 2 hours at 2 hours, and the aromatic polycarbonate of the viscosity average molecular weight 20,000 was obtained.

&Lt; Example 14 >

[(A) step]

In a stainless steel reactor consisting of a 27.1 mm inner diameter and 500 mm high tube, a solid catalyst supported by 0.5 wt% of palladium in a pellet-shaped a-alumina having a diameter of 5 mm and a length of 3 mm was charged. After passing hot water through the shell side of the reactor to maintain the temperature of the catalyst layer at about 100 ° C, the raw material gas (composition: carbon monoxide 22.0 vol%, methyl nitrite 10.0 vol%, nitrogen monoxide 4.0 vol%, methanol 5.2 vol%, carbon dioxide 1.7 vol% , 57.1 vol% of nitrogen) was supplied at 1.15 Nm 3 / h and 0.2 MpaG to prepare dimethyl oxalate.

The gas having passed through the catalyst layer was led to the bottom of the gas-liquid contact absorption tower having an inner diameter of 43 mm and a height of 1000 mm, and at 0.42 L / h of methanol introduced from the top of the column and at about 35 ° C. Countercurrent contact was made. Then, 0.3 kg / h of condensate (composition: 42.6% by weight of dimethyl oxalate, 1.8% by weight of dimethyl carbonate, 0.03% by weight of methyl formate, 42.6% by weight of methanol) was obtained from the bottom of the column, and a non-condensable gas (composition: 16.2% by volume of carbon monoxide) was used in the column top. , 4.9% by volume of methyl nitrite, 8.1% by volume of nitrogen monoxide, 15.9% by volume of methanol, 1.8% by volume of carbon dioxide, 53.1% by volume of nitrogen), and 1.23 Nm 3 / h were obtained.

0.33 L of methanol introduced into the non-condensed gas into the bottom of the gas-liquid contact regeneration tower having an inner diameter of 83 mm and a height of 1000 mm was mixed with a gas of 13.8 NL / h of oxygen and 0.5 NL / h of nitrogen monoxide. Counter-current contact with / h and nitrogen monoxide in the gas was regenerated in methyl nitrite. Regeneration gas derived from the top of the regeneration tower (composition: carbon monoxide 18.2 vol%, methyl nitrite 10.4 vol%, nitrogen monoxide 4.2 vol%, methanol 5.4 vol%, carbon dioxide 2.0 vol%, nitrogen 53.0 vol%) 1.1 Nm3 / h ( 2.1 kg / cm 2 G) and 49 NL / h carbon monoxide (2.1 kg / cm 2 G) were fed to the reactor.

Since 0.48 L / h of methanol containing 5.7% by weight of water derived from the bottom of the regeneration tower contains a small amount of nitric acid, after neutralization with caustic soda, water is removed by distillation and It was reused as a methanol source.

On the other hand, the condensate was batch-distilled for 50 hours in a distillation column (top bottom capacity 100L) of 150 mm inside diameter and 7500 mm height. And 5.8 kg of dimethyl oxalate of 99.9 weight% of purity were obtained.

[(B-1) step]

Diphenyl oxalate was manufactured as follows using the dimethyl oxalate obtained at the (A) process.

A bottom was extracted from the bottom of the reaction distillation column for catalyst synthesis obtained in the same manner as in Synthesis Example 1 while supplying a mixed solution containing 54.5% by weight of phenol and 45.5% by weight of dimethyl oxalate from the top of the first reaction distillation column. The solution (phenol solution of TTP) was fed at 18 ml / h. The bottom of the first reaction distillation column was heated to 190 ° C, and the transesterification reaction was carried out while condensing the vapor from the tower portion with a cooler and extracting it at reflux ratio 2.

At the time when the state of the tower was stabilized (4 hours after the start of supply), the composition of the column bottom liquid was 6.23% by weight of diphenyl oxalate, 29.95% by weight of methyl phenyl oxalate, 23.88% by weight of dimethyl oxalate, and 39.41% by weight of phenol. Was about 603 g / h. At this time, the liquid having a composition of 98.0% by weight of methanol, 0.9% by weight of dimethyl oxalate, and 1.1% by weight of anisole was extracted at about 44 g / h.

[(B-2) step]

The bottom liquid of the transesterification reaction (the bottom liquid of the first reaction distillation column) is supplied at 600 ml / h under a reduced pressure of 200 mmHg from the top of the first reaction distillation column and the second reaction distillation column of the same type, and the second reaction distillation column The bottom of the was heated to 200 ° C, the vapor from the tower was cooled, and a heterogeneous reaction was performed.

At the time when the state of the tower was stabilized (4 hours after the start of supply), the composition of the column bottom liquid was 65.27% by weight of diphenyl oxalate, 18.43% by weight of methyl phenyl oxalate, 1.02% by weight of dimethyl oxalate, and 13.93% by weight of phenol. Was about 252 g / h. At this time, a liquid having a composition of 1.57% by weight of methanol, 2.97% by weight of dimethyl oxalate, 48.51% by weight of phenol, 2.97% by weight of methyl phenyl oxalate, and 0.42% by weight of diphenyl oxalate was extracted at about 355 g / h.

[(B-3) step]

The bottom liquid of this heterogeneous reaction (the bottom liquid of a 2nd reaction distillation column) was supplied to the thin film type | mold evaporator, and dimethyl oxalate, phenol, methylphenyl oxalate, and diphenyl oxalate were continuously evaporated. The obtained steam was supplied to a distillation column to carry out continuous distillation. Then, 3.05% by weight of dimethyl oxalate, 41.73% by weight of phenol, and 55.21% by weight of methyl phenyl oxalate were extracted from the top of the distillation column at about 68 ml / h, and 99.7% by weight of diphenyl oxalate from the bottom of the column. Was extracted at about 120 g / h. At the bottom of the evaporator, a liquid containing about 2.5% by weight (in terms of metal) of titanium was extracted at about 14 g / h.

[(C) step]

The distillate (composition: 98.0 weight% of methanol, 0.9 weight% of dimethyl oxalate, 1.1 weight% of anisole) extracted from the tower top by the transesterification reaction of the dimethyl oxalate and phenol of the process (B-1) was used at the process (B-1). Methanol was purified using the Aldershow. Distillation conditions were carried out at atmospheric pressure and reflux ratio 1. As a result, the oil obtained from the column top was methanol containing dimethyl oxalate below the detection limit (1 ppm or less) and anisole containing 18 ppm.

[Use of Recovery Methanol to Step (A)]

Dimethyl oxalate was produced in the same manner as in Example 14 using the recovered methanol obtained in the step (C). From the step (A) to the step (B-3), the same results as in Example 14 were obtained.

&Lt; Example 15 >

200 g of oxalic acid diphenyl ester obtained in Example 14 and 1.55 g of tetraphenylphosphonium chloride were added to a 300 ml volume round bottom flask equipped with a thermometer and a stirring device, heated by a mantle heater, and de-CO2 at 250 ° C. for 2 hours. The reaction was carried out. During the reaction, generated carbon monoxide was released out of the system from the exhaust pipe connected to the reactor. The composition of the reaction solution in the reactor was analyzed by gas chromatography to obtain 98.1% by weight of diphenyl carbonate and 1.1% by weight of diphenyl oxalate.

In this state, a solution obtained by dissolving 0.5 mol% of tetraphenylphosphonium chloride in diphenyl oxalate obtained in Example 1 was supplied to the reactor at 70 ml / h, and the reaction solution was continuously discharged to maintain 200 ml. It was. In addition, the mantle heater was controlled to maintain the temperature in the reactor at 250 ° C. When the composition of the reaction liquid became stable (about 10 hours after the start of the continuous reaction), the extraction liquid was analyzed to find that 91.2% by weight of diphenyl carbonate and 7.8% by weight of diphenyl oxalate were used. In addition, carbon monoxide was generated from the reactor at about 110 ml / h, and the purity was almost 100%.

&Lt; Example 16 >

Dimethyl oxalate in the same manner as in Example 1 using the distillate (composition: 98.0% by weight of methanol, 0.9% by weight of dimethyl oxalate, 1.1% by weight of anisole) extracted from the column top by the transesterification reaction of dimethyl oxalate and phenol of Example 15 Was prepared. Initially, the same results as in Example 14 were obtained from step A to step B-3, but the reaction yield tended to decrease gradually with time.

<Examples 17 to 19>

In order to investigate the influence of anisole in the dimethyl oxalate reaction step, dimethyl oxalate was synthesized by using a jacketed SUS reaction tube with an inner diameter of 20 mm. 5 ml of pellet-like solid catalyst as in Example 14 was charged into the reaction tube, and the temperature of the catalyst layer was controlled to be 120 ° C. by passing the jacket through a heating medium, while carbon monoxide 22.0 vol%, methyl nitrite 10.0 vol% and nitrogen monoxide 4.0 Dimethyl oxalate was synthesized by supplying a mixed gas of 22% by volume, 6.2% by volume of methanol, and 57.8% by volume of nitrogen at 22 NL / h and 0.2 MpaG. In addition, in order to examine the influence on the reaction of anisole, a predetermined amount of anisole was added to the mixed gas and supplied, and dimethyl oxalate was synthesized. The results are shown below. In addition, in Table 6 below, the activity lowering rate is the STY lowering rate per 1,000 hours.

STY in Table 6 is a published quantity (Space Time Yield), and represents the quantity in a unit time per unit capacity of a reaction vessel.

From the results in Table 6, if the ether content in the alkyl alcohol removed in the alkyl oxalate (B-1) step is 1000 ppm by weight or more, the catalytic activity is lowered in the step (A) in which alkyl alcohol is used by recycling, resulting in a catalyst lifetime. It was found that this shortened.

Claims (23)

A method for producing diaryl oxalate comprising the step of transesterifying a dialkyl oxalate and / or an alkyl oxalate with an aryl alcohol in the presence of tetra (aryloxy) titanium as a catalyst,
Tetra (aryloxy) titanium is fed into the reaction system of the transesterification reaction as an arylalcohol solution of tetra (aryloxy) titanium by reacting tetraalkoxytitanium with an excess of arylalcohol and removing the by-produced alkylalcohol. The manufacturing method of diaryl oxalate. The method for producing diaryl oxalate according to claim 1, further comprising distilling and purifying the titanium compound concentration of the reaction solution containing diaryl oxalate to 10 ppm by weight or less. The method for producing diaryl oxalate according to claim 1, wherein the material of the apparatus in contact with the reaction solution of the transesterification reaction is austenitic stainless steel containing 1 to 4% by weight of molybdenum while containing 10% by weight or more of nickel. The process of claim 1, wherein the step (A) of preparing dialkyl oxalate by reacting carbon monoxide, oxygen, and alkyl alcohol,
(B-1) a step of reacting dialkyl oxalate obtained in step (A) with aryl alcohol in the presence of an aryl alcohol solution of tetra (aryloxy) titanium to produce alkylaryl oxalate while removing the resulting alkyl alcohol,
The alkylaryl oxalate obtained in step (B-1) is heterogeneously reacted in the presence of an arylalcohol solution of tetra (aryloxy) titanium to produce diaryl oxalate while removing the resulting dialkyl oxalate and alkyl alcohol. 2) process,
(B-3) step of separating and recovering diaryl oxalate obtained in step (B-2)
Including,
The manufacturing method of the diaryl oxalate which recycles alkyl alcohol to (A) process through the process (C) which makes the ether compound content in the alkyl alcohol removed at the process (B-1) less than 1000 weight ppm. The method for producing diaryl oxalate according to any one of claims 1 to 4, wherein the tetra (aryloxy) titanium is tetraphenoxycitane. The method for producing diaryl oxalate according to any one of claims 1 to 5, wherein the tetraalkoxy titanium is tetraisopropoxycitane. The reaction between tetraalkoxy titanium and an excess of aryl alcohol according to any one of claims 1 to 6, wherein the molar ratio of the titanium atom and the aryl alcohol in the tetraalkoxy titanium (arylalcohol / titanium atom) is from 10 to 80. Method for producing diaryl oxalate to be carried out. The process for producing diaryl oxalate according to any one of claims 1 to 7, wherein the reaction of tetraalkoxy titanium with an excess of aryl alcohol is carried out while maintaining the reaction temperature at 160 to 300 ° C. The method for producing diaryl oxalate according to any one of claims 1 to 8, wherein the reaction of tetraalkoxy titanium with an excess of aryl alcohol is carried out in a reaction distillation column. The method for producing diaryl oxalate according to claim 9, wherein the reflux ratio of tetraalkoxytitanium and excess aryl alcohol in the reaction distillation column is 3 to 40. The reaction distillation column according to claim 9 or 10, wherein the tetraalkoxy titanium and the excess aryl alcohol are continuously added so that the molar ratio (aryl alcohol / titanium atom) per unit time of the titanium atom and the aryl alcohol in the tetraalkoxy titanium is 40 to 80. Process for producing diaryl oxalate supplied. The method according to any one of claims 1 to 11, wherein tetraalkoxy titanium and an excess of aryl alcohol are supplied to a reaction distillation column for reaction, and an oil fraction containing an by-produced alkyl alcohol is extracted to form a bottom portion. Production of diaryl oxalate to obtain an arylalcohol solution of tetra (aryloxy) titanium from which by-produced alkylalcohol was removed by extracting an oil containing tetra (aryloxy) titanium and arylalcohol from the product. Way. 13. The process of claim 12, wherein tetra (aryloxy) titanium and arylalcohol are continuously extracted from the bottom of the reaction distillation column, and the arylalcohol solution of tetra (aryloxy) titanium which is subsequently removed by-product alkyl alcohol is transesterified. Method for producing diaryl oxalate to be supplied to. The manufacturing method of the diaryl oxalate of any one of Claims 1-13 whose material of the apparatus which contacts the reaction liquid of a transesterification reaction is an austenitic stainless steel containing 16.00-18.00 weight% of chromium. 15. The process for producing diaryl oxalate according to claim 14, wherein the material of the apparatus is austenitic stainless steel substantially free of nitrogen atoms. The method for producing diaryl oxalate according to claim 15, wherein the material of the apparatus is SUS316-based austenitic stainless steel defined in JIS G 4304. The method for producing diaryl oxalate according to claim 16, wherein the austenitic stainless steel is SUS316 or SUS316L defined in JIS G 4304. The process for producing diaryl oxalate according to any one of claims 1 to 17, wherein the apparatus is a purification tower of diaryl oxalate, a reaction vessel of a transesterification reaction, or a reaction distillation column. The method for producing diaryl oxalate according to claim 4, wherein the ether compound content in the alkyl alcohol is 300 ppm by weight or less in the step (C). The process for producing diaryl oxalate according to claim 4 or 19, wherein the ether compound in the step (C) is alkylaryl ether. The oxalic acid ester having at least one aryl ester group or a decomposition product thereof according to any one of claims 4, 19 and 20, wherein the oxalic acid ester having at least one aryl ester group is a Fries rearrangement compound, and a hydroxyl group. And a compound having an aryloxy group, or a compound in which a hydroxy group and an aryloxy group of the compound react in or between molecules, or a derivative thereof. The manufacturing method of the diaryl carbonate which decarbonylates the diaryl oxalate manufactured by the method in any one of Claims 1-21 in presence of a phosphorus compound. A method for producing polycarbonate, wherein diaryl carbonate produced by the method according to claim 22 is reacted with bisphenol A in the presence of a basic alkali metal salt.